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Tire testing. Recommendations.
Wheels, rim shapes, spacers, nitrogen, wet roads,  tire
markings, hydroplaning, etc.
Tire wear.

  Copyright, 2014, R. Fleischer

http://bmwmotorcycletech.info/section5.htm
article #54, section 5




Preliminary:

It is difficult to maintain a list of recommended tires due to changes in what is available; and, what I have ridden & tested.  Up until around year 2005 I was putting on rather high mileages every year; and, testing riding many Airheads besides my own; PLUS, my tire testing was vigorous ...& rather formal. As I type this in December, 2016, I will be 80 next year.  I am putting on far fewer miles these days, & I have been slowly reducing the vigorousness of testing.  I will no longer be testing tires nor riding nearly as hard.  Effective October, 2016, for two-wheelers, I will no longer be doing the following:
(1) on-purpose corner sliding; 
(2) full-on panic-stopping on both dry & wet roads. 


In the past I had not often included other's remarks about tires that I had not personally ridden & tested.   I now have three people, whose serious tire testing mirrored mine close enough. I have begun to include their input.  I list some discontinued tires on purpose, for reference & comparison; ALSO, Some old style tires are now being re-made, often with updated rubber and possibly construction. 

MORE information is located in:  
http://bmwmotorcycletech.info/wheels.htm      
Detailed information on wheels, and see next line too....


http://bmwmotorcycletech.info/section6.htm   
Gets heavily into tube & tubeless,
on various rims.


http://bmwmotorcycletech.info/tirerepair.htm   
Gets heavily into tire repairs, and LOTS more information. Read this one!!



Some words of caution, & STRAIGHT TALK: 

Some tire testing is easy & this is the type MOST TYPICALLY reported or commented-on (Lists, Forums, ETC).  Mostly JUST OPINION, with LITTLE REAL FACTS.  Sometimes it is not even real opinion, but someone wanting to say something to feel part of the group.

Better type of commentary comes from those who generally do the following things:
You keep your tires inflated properly.   You ride like you usually do, mostly on paved roads with mixed speeds, and are willing to state accurately the types of speeds you use because speed affect tire wears to quite some extent.  You do mixed type of curves, mixed type of road roughness, mixed loading.  If you ride two-up a lot, you note that in your records.  If your loading is high, you note that.   You write down the odometer reading when you put the tires on & when you take them off for replacement.  Perhaps you always replace tires when the center of the tread is 1/16" deep. If not, you make note.  You write the mileage down, subtract, & now you have YOUR typical mileage for YOUR usage on THAT tire, at YOUR weights/loading, speeds, & tire pressures.  Perhaps you do testing at various tire pressures before beginning the ride.  Maybe you write down how easy, or how difficult it was to mount the tire.  This can all be useful information.  But, in your 'opinions', do you specify EXACTLY all the facts about riding style, pressures, loads, types of roads ... & many other things?  If you say you are aggressive, JUST WHAT DOES THAT REALLY MEAN?   Would you be able to write a report, that not only gives real testing facts, but recommendations made from honest comparisons against many other brands & models, ETC.?

Typical comments on various forums when discussing motorcycle tires is about "how well the tire sticks to the road"; & how many miles before it wore out.  In a rather large percentage of instances, no 'standards', only minimal information opinions, are seen in discussions.  The bald truth (BAD pun!) is that modern tires are vastly better than the tires were when your Airhead was manufactured (particularly before the mid to late eighties), & unless you have REAL racetrack experience, you are UNLIKELY to be capable of putting the tire to real testing, let alone out-riding the tire.   Have you REALLY tested/ridden to see if/when/how/conditions that the front wheel looses traction?  When does it lose the 'sticks to the road' performance you posted about....?   What about your bike's suspension ...it has a HUGE amount to do with how the front tire 'sticks' to the road, particularly if the road is not dead-perfectly flat 100%.    I'm not overly nice, am I?

Your Airhead is of limited power, limited braking, & may have suspension aging or improper setup problems ...all of which affect tire life (AND handling!). Even when a number of modifications are made, these are still NOT 170 mph crotch rockets.

Serious accidents can occur with something as simple as a tight turn, especially at speed, especially with a rear tire tread that has been worn more than somewhat (the center of the tire tread flattened), when it originally was rounded to some degree. Do you KNOW about flat-worn rear tire stability problems?  If you had a motorcycle that went into high speed wobbles or oscillations, would you blame the bike, the rear tire, maintenance of some 'guessing' sort, or, just what would you say, publicly?  Is the 'report' USEFUL? ACCURATE?

IF you tried to duplicate my style of testing when I was younger & the testing or at least educated experience from those who ACTUALLY put their tires 'to the test', perhaps on racetracks, or in serious dirt conditions ...you could be asking for serious trouble.  You probably know this, yet probably don't want to admit it.

ASK YOURSELF: Are you REALLY competent at riding to the tire slipping point, over and over again, on purpose?  What about crossing up the steering during sliding? Does that idea of crossing-up the steering freak-you out?  On wet roads?  What about when your beautifully executed carving turn encounters lots of bumps? Sudden off-banked tight turns?  Washboards?   Can you truly (be honest!) feel the difference a FEW pounds of pressure makes?   Have racetrack & soft dirt/gravel & wet roads experience?    Are you truly smooth with the controls (including transmission, brakes, clutch & throttle)?  Are you smooth with transitions from any surface or turn direction, etc.?   Tires DO vary considerably, in how they handle, how they wear, & under what types of conditions (including road surfaces, straights, turns, off-banks, braking in dry good friction areas versus wet roads ....what about deeper water on those roads? 
What characteristics of a tire do you REALLY need?   Be honest with yourself!   Even in an 'emergency maneuver', ask yourself just how much you would really push your tires.   Do you know that super-performance tires may well NOT be the type YOU should use?  Do you know why this is so?

PROBABLY quite a number of tires will work well for most any type of riding you do.  BUT, you MAY be the type of rider that really IS aggressive, or has special needs.  Perhaps you really do ride off-road, into seriously soft stuff, mud, single track trails, real Adventure Riding ...are you going to ride on pavement to get there?  Maybe you really ARE an aggressive road rider, maybe you get off-road now and then, maybe only into mild dirt and abrasive gravel?    Perhaps you, like most motorcyclists, love carving turns at speed on paved roads.  Are those turns nice sweepers, or tight twisties on, perhaps, narrow roads?  What about the FEEL of your tires in tight twisties, especially when very quickly changing directions? Perhaps you REALLY use the front brake truly hard.  Do you brake aggressively in turns?  Would you know how?  Are you carving the same turns quite precisely, turn after turn?  Perhaps you ARE a real all-weather rider; maybe you use your motorcycle as your primary transportation, year-round.  Riders have different real needs for their tires.

I tried to cover most all uses & rider types for specific tires.  Since there is so much interest in tires, I offer a fair amount of information in this article.  I will try to separate anecdotes from facts. I try to separate those whose input comes from racing experience, from those with road experience.  I try to do THAT in several ways.   Keep in mind that when a very experienced track racer rides a bike on the streets & highways, their expressed viewpoints about their tires tends, rather strongly, to be a comparison between how a RACE BIKE handled on a RACETRACK with REAL racing tires ...compared to what the street bike (which may even be a high performance type) feels like on street-riding tires.  THIS MAY NOT BE OF REAL VALUE TO YOU ...the average, ...even somewhat aggressive ...street rider.   In MY experience, SOME real racers are milder in street riding than you may think ...but, they ALSO may be VERY aggressive AT TIMES in such as tight twisties.  Thus, their remarks about tire feel & mileage may be very different from your input, even if you say, & possibly ARE, aggressive in your riding. 

Do YOU square off your rear tire in your riding? ...do you wear the sides of the tread very noticeably?  How do reports from these various types of riders vary?  Why?  Will YOU ever ride in the twisties to even close to the extent & aggressiveness of someone with a LOT of track experience, particularly on track type racing tires?   If YOUR proposed tires are a type that such expert and aggressive riders like, will YOU like them?

Did you KNOW that quite high performance tires can be dangerous to non, or moderate riders?
   There ARE reasons to NOT get the "best" tire, whatever that word will mean.

Be VERY cautious about whose words you listen to (and try to emulate).  ULTIMATE road performance to modern performance standards MAY WELL not be what YOU are going to be REALLY interested in ...and those tires may not give you mileage and value ...and might feel twitchy, etc.  You may be disappointed in the tires (or, worse, you describe them as wonderful, when you do not really believe that ...worse yet, if you can't really feel differences and so describe them as wonderful).

Discussions about tires tends to be like talk over a few beers around the campfire, or 'garage racing'.  In MANY instances, stated viewpoints on their own tires are NOT substantiated by real testing.  I hope to provide REAL information in this article.   Tire threads can be like oil threads on internet lists!

I RECOMMEND YOU DO NOT TRY TO DUPLICATE MY TESTING METHODS UNLESS YOU ARE COMPETENT TO DO SO, & ARE WILLING TO TAKE ON THE RISKS OF DOING SO.  I AM NOT RESPONSIBLE FOR YOUR INCIDENTS & ACCIDENTS!

When I first began this article, long ago, I incorporated a lot of testing notes that I'd done over a lot of years; AND, I had a large section on EXACTLY how to DO tire testing; that is, very specific step-by-step methods on different types of roads, to initiate instabilities, to test sliding, braking, suspension wiggles/oscillations........and, to actually TEST how tires REALLY stuck to the road (front and rear), on both dry and wet roads.  The details explained how to get into the test, perform it, and how to get out of the testing regime safely.   TWO people got into trouble, one ran his bike into a metal side railing on a highway, and the other flipped his bike from wrong use of the brakes ...and did a LOT of damage. Quite luckily, neither was seriously injured. I had conversations with both of them.  For BOTH, the problem was that they DID NOT follow directions, and DID NOT do the small steps I outlined that would safely allow them to work up to be more aggressive .....AND, another way of saying this is that they did not having the skills when panic set in. I removed the entire section, and have no intention of returning it to this article.  I now will only say that those with some goodly dirt riding experience will do better at road situations when testing tires, suspensions, etc.

Most of my testing was done on a variety of Airheads.  Some few were done on classic K-bikes.  In a number of instances, I tested on other folks motorcycles;  rather rarely on other makes of bikes, and not reported on unless also tested on Airheads and/or K bikes.   I also tested on two models of Ninja's, but the results are NOT shown here, as the handling/feel on a Ninja is NOT comparable to a BMW Airhead, nor a BMW Classic K bike.   In general, my remarks are for Airheads, unless specifically stated otherwise.

While I really would like to do occasional aggressive riding,  the facts are that I tire more easily, I have less stamina, I am weaker from the slow part of aging that reduces one's muscles.  True tire testing takes real muscling around the bike, and Airheads are not light weight.  I decided to set a date, after which I would tone down my riding and tire testing protocols.  Done.
 

I have been blessed in my old age with good reflexes & eyesight.   I live in an area that has a variety of terrain, including all sorts of types of twisties in mountain passes.  There are some sand areas (these "Sand Pits" were actually set aside for motorcycles only), 3 miles from my home.  My paved-road testing area gets mixed weather conditions; has various pavement styles & conditions & more than one type of tire snake compounds.  A few years ago, the State of Nevada did some paving repairs near here, where they 'tested' a new type of tar snake compound.  It was a disaster & they had to remove it.  I did a lot of stiction & tire skipping testing on that 11 miles or so of road, on both types of tar snakes too. BUT, I could not use the aggressiveness I wanted to, on that particular road, due to the traffic (and the Authorities).

Some areas near here that I use are fairly flat & smooth with excellent pavement.  One area has very ugly curvy (poor workmanship!) rain grooves & this same road has some broken and uneven pavement sections. I also have a freeway 26 miles distant (with & without rain grooves sections).  There is a road where I have done very high speed testing on (in conjunction with my association with a bike magazine; no, you will not be told who/where).    I also have two dirt areas, one is medium hard-pack;  one is very soft & deep sand/gravel (that one is, as noted above, is only 3 miles from my home).   On the rare occasion I got on a racetrack with a bike, I noted the types of tires; how they feel/handle, pressures, etc.  

ONCE IN A WHILE I have specifically tested a bike that has a squared-off rear tire, doing this for stability testing of the entire bike besides tire feel. Same for suspension, stiction problems, etc.  I also try to test bikes, when I can, that have large windscreens or fairings, perhaps with tour bags & a backrest ...to see how they handle various speeds & direction changes.  In other words, I may combine bike & equipment testing with tire testing!  I've even tested bikes with one large rear saddlebag, and same bike with two; this was done on purpose to see if oscillations could be induced.  In fact, this type of testing was done in the Spring of 2016 on my own R100RT.

For NEW tires, my habit is to run the tires in reasonably for 50 to 100 miles, slowly increasing aggressiveness over those miles. I make notes, play with tire air pressures (I take along a small electric compressor & I use a very accurate Bourdon type gauge) ...& when I find hot/warm pressures that work well, I recheck with the tires cool, so I know what the normal tire pressure should be (tire pressures for normal use are initially checked with the tires cool, that is, not ridden yet).

Testing informs, for any one particular bike, how a tire can be expected to work ...this testing should include panic situations & pushing things aggressively in various types of turns.  I like to do sharp corrections in mid-turn for additional information.    Properly done, testing allows comparison between various tire makes & models; & THIS IS MY PRIME GOAL.  

I have certain testing areas very close to my home in California that I have consistently utilized since 1973, depending on time of year and conditions.  One area has THREE moderately steep & twisty mountain passes.  They have a mix of asphalt & cement surfaces & a mixture of tar snake repairs (excellent for testing suspension stiction). One stretch of road is often irregularly flooded in the Springtime with water for distances of 1/4th to 1/2 mile (I use it for curves & braking tests).  This area has both rough, broken and smooth pavement.  One area that seems to always be dry has rather rough & uneven pavement.  That area also has off-camber curves!  Off-camber curves are very interesting when testing tires that are fairly well-worn, and ""NOT fun"" with flat-worn rear tires.


The rest of the details, before I get into the brands and testing results (followed by Everything Else):

1.  Some types of tires do/did not work well on early Airhead motorcycles.   TIRES BACK THEN REQUIRED LOWER TIRE PRESSURES. CONSTRUCTION OF THE TIRES WAS QUITE DIFFERENT THAN TODAY'S TIRES. Today's tires, with very few exceptions, use higher pressures, in some instances up to 10psi more. Failure to increase to proper pressure will give poor handling, particularly during transition from straight ahead to a turn.   You can NOT depend on the tire maker to tell you the proper pressure for BMW Airheads particularly the more older Airhead bikes  ...they may want to limit any possible liability, so they simply quote what BMW said in original OLD literature.

Almost 100% of modern tires require HIGHER pressures than BMW recommended, and used, with old style tires from when the early Airheads were being sold. Since the mid-eighties, this has been LESS SO, and Owners Booklets pressures are closer, or actually, what is now needed, particularly since the end of the eighties to 1995.

We now even have special radial tires for 'classic' motorcycles like our Airheads & the Classic K bikes.  Most do VERY well.  I think most of you will actually like these new radial tires ...even mild riders.  Many of the newer non-radials are also excellent. BE SURE you use appropriate pressures in all tires.

LOWER profile tires (modest, such as 80 section) may not work well (exceptions depending on the tire, and if a Monoshock or Paralever, or a Classic K bike), & many simply will not properly fit old Airheads, they will rub something, especially the swing arm.   Generally a "90"  profile works best on old Airheads.  Unless I specifically make note in this article, your should assume that I used the stock tire sizes, or close metric 'equivalent'.   I tried, when I could, to test inch sizes (when available, many tires are not available in inch sizes).  Example:  4.00 x 18 rear original. Test in 4.00, 110, and 120.  Another example:  3.25 x 19 front original, test in 3.25, 3.50, 90/90, 100/90.  Similarly for the 18" front tires.   In order to do some types of testing I had to be putting on huge mileages every year ...and I did ...I have my 600,000 BMW badge and credentials.

2.  Frames & suspensions were designed by BMW for a specific feel & handling that BMW desired.  Many seem to have no idea that frame design & construction, suspensions, & MANY other things, ALL, together, affect how a motorcycle feels, & one word is often used, without specifics:   HANDLING.  In common use are such terms as FEEL, TURN-IN, FALL-IN, TWITCHINESS, QUICKER-Handling, ....& other words ...... that you might think mean something very specific.

3.   BMW used to issue bulletins with names/models/sizes of tires that BMW HAD TESTED & APPROVED; but that has not been done for Airheads since they were in production (with some very few exceptions).

4.  Here is a link to a rather nerdy article.   The article has extensive vector & other diagrams, & some conclusions about contact forces that may well astonish you.  When you read it, keep in mind what REALLY happens when you are cornering.  THINK about the effects of you changing a tire size ...from, an example here, a 90/90 to a 100/90.  What REALLY happens when you go to a larger size tires (larger width).  You may be very interested.
http://www.goldwingfacts.com/forums/10-reference-faq-forum/400426-design-differences-between-car-motorcycle-rim-tire.html

The article has some real jewels of information here and there, in-between the nerdiness. It really is worth the read.  It is one article, followed by dozens of pages of commentary from others; feel free to look at them.  Amongst the 'jewels' in the article are the definitive details on rim shapes and dimensions of such as motorcycle tire bead areas (thickness and shape too) versus car types; and, the facts about why friction (traction) is INDEPENDENT of contact area ....and why wider tires are used to obtain better WEAR from otherwise less-mileage stickier rubber compounds. 

If you are a sidecarist, you may be interested in that article for several reasons, including the rim shapes, friction details, etc.    Some sidecarists use small car tires on motorcycle wheels. Most sidecarists know about the differences in stated rim diameters, when trying to put a car tire on a bike rim, and vice versa, but few know about the bead width, and other details. 

You may also be interested in the information on rim shapes in this article:
http://bmwmotorcycletech.info/section6.htm

5.  Many if not most all of the tires from the seventies, even many from the eighties & nineties ...are no longer available, except for a few, including the classic Continental RB2 and K112, and now some re-incarnations of Metzeler 'Heritage" tires & the Bridgestone Accolade. Those Continental front tires, like all ribbed tires, unfortunately, follow rain grooves.  Rain-groove-following is a problem with all straight ribbed front tires & some others with irregular treads. There are tires available now that have only one center rib, usually wider than the old narrower grooves/ribs & are typically somewhat better on rain grooves.  Tires withOUT center ribs of any sort generally do not usually follow rain grooves, but there are exceptions; usually the instabilities are mild.   Some folks are very much bothered by the feel of their bike when the tires track rain grooves, other riders are not bothered, simply accepting the feel, and prefer the characteristics of that particular tire.   SOME types of bridge gratings can cause an even more disturbing situation, depending on the types of gratings ... & can cause a goodly pucker factor; even more increased concern if the gratings are wet from rain.   Not many ride on original type of ribbed front types, and one reason is that they DO, often seriously, follow rain grooves, contrary to what is said in some Clymer's publications.  Still, you MAY want to try a set, as some can deliver the classic ride & handling that your bike was designed-for.   THESE TIRES MAY work best at the originally recommended by BMW tire pressures (label was under the seat, see your owners manual too), or slightly higher (typically by 2 psi front, 3 psi rear).  I recommend that if you run these classic tires that you inflate to the TWO-UP and/or high speed pressures shown in the Owners Booklet.  These tires give reasonably good mileage before they wear out.   If you have a modified suspension, the classic ride & handling will be modified.  Do NOT mistake these (original make, model, & name) ribbed tires for the modern tires advertised as being for 'classic bikes'.   There were also non-ribbed front tires made when the /5 and /6 were still being sold brand-new ...and the same cautions about tire pressure apply ...some are being reproduced.

One of the problems with trying various classic/heritage (or similar) tires is that MOST riders no longer have the exact same type of original shock absorbers & springs; or, those are not in good condition; or, other parts of the motorcycle have aged; or, they have made other changes. Just changing the type or style of handlebars WILL AFFECT the bike feel.  If your bike is in reasonably decent condition & reasonably close to original specifications, you might really want to try a set of the old tires (which might well have some changes in them, so you might NEVER REALLY get the exact original feel as when the bike was brand-new).  It REALLY IS worth trying these tires if you want to experience something close to original feel.  If you don't like the tires, sell them to someone else.  

6.  I have personally ridden on quite a few modern tires, besides the really old type tires.  MOST modern road type tires offer rather good road handling, quite decent predictability of handling in various situations, indication to the rider of what the tires are doing AND GOING TO DO; as well as comfort, load carrying, traction in cold/wet/dry & not unreasonable differences in handling between moderately wet & dry.  A few don't let you know about handling limits ...until you are suddenly very aggressive, particularly back and forth quickly.

One thing usually discussed, MILEAGE (tire wear), SHOULD NOT be "the" most important characteristic for most riders, although for some folks, who put on large yearly mileages, that can be of more importance ...so I DO get into comments and recommended tires for mileage.  MANY of today's tires, including re-incarnations of old styles, will have better mileage than long ago, even though these modern tires are not being sold as 'high mileage'.  That is due to the use of different proportions of carbon black and silica's, and the increasing use of different tire compounds in the center versus the sides. 

7.  There is a considerable difference in how tires FEEL to the rider & also differences, large ones, with various models of BMW Airhead motorcycles.  Trail & suspension & wheel width differences are only a quite modest portion of the reasons.  MOST ALL modern tires are capable of out-handling the bike & MOST RIDERS.  They stick to the road rather well, even at big lean angles under fairly severe conditions at speed.  That's the truth.  BUT, there is another truth:   the FEEL can make the rider THINK the bike is handling wonderfully; OR ...poorly.  When reading tire comments/reviews, FEEL is NOT well differentiated. 

MANY modern tires have profiles, type of rubber, type of design, type of tread, ETC., that give a "quicker handling" feeling.  Many modern tires FEEL to the rider, particularly when starting out on a new set of tires they have not ridden on before ...that they are considerably OVER-inflated, & might be called SKITTERY.  'Quicker Handling' is often the term used by those riders.  Many riders are timid, particularly on wet roads ...but, the tires may feel ...or be described ...as quick, or twitchy, or skittery, etc. ...on dry roads too, even after thousands of miles on the same tires. 


Another truth is that riders transitioning to a modern tire that REQUIRES increased inflation pressure, might be using OUTDATED tire pressure information.  This results in a very poor handling tire, typically a mushy-ness, tire-rolling sideways on the rim type of feeling.  MANY will equate THAT feeling with being skittery ....which is not really true.  Still, the effect is BAD HANDLING.

Wet roads (and maybe even hard packed dirt and thin gravel) tend to create a considerable apprehension for many riders.   Many riders did not experience wet roads much when learning to ride & are slightly to moderately freaked-out by the idea of riding in rainy conditions.   In MY experience as a guide/teacher, these types of riders may also especially freak-out on gravel or dirt roads ...even at just the thought of being on gravel roads.  I KNOW riders who are NOT going to attend a function, such as a TechDay, etc., if the driveway is gravel or steep.   This is not an article about how to ride bikes, I am just telling the truth about various riders.   If a rider is ACTUALLY timid (hard to find out!), how much weight will you give to this rider's opinions about tires?   MAYBE YOU SHOULD pay attention ...you might be similar!!   The truth is that most motorcyclists are NOT after anything hardly approaching racing experience.  Many do NOT want to ride aggressively; BUT... most do want to be brisk now and then.  MANY are OLDER (especially BMW riders) & don't like 'taking chances' (which words have different meanings to various riders). Many riders are simply out for a "Gentleman's ride on Sundays"; or a mild to modest ride to a TechDay or camp-out.  It is true, also, that many, if not most,  like some occasional aggressive fun in twisties and sweepers.   THAT is not usually the same as the aggressive rider who, turn after turn, pushes his bike hard into corners, and likes nothing more than a long series of VERY connected corners....or, someone who actually races on a track.

I consider all riders in testing/talking about tires.  I try to analyze tire performance for ALL USERS.  The exception is REAL RACING, where skills are likely quite high, aggressiveness is a given, special tires are in use as are special techniques ...such as pre-warming the tires in the pits, wearing sidewalls rapidly, speeds are high ...& quite a few other things. I have not, but seldom, reported on true racing tires, and not in THIS article.


8.  Mileage one gets from tires depends on speed, loading (you, any passenger, luggage, etc), tire pressure, road condition, temperature (including road surface temperature), style, etc.  Be very cautious about who you listen-to.   You may want to ask very detailed questions!

9.  MUCH of what I hear and read about tires seems to be based on nothing but thin air, or ...the owner has purchased them & WISHES they tested as he says they do. The rider may have NO IDEA of what he is talking about.   I realize this is cynical, but it is the truth.  I am WELL-AWARE that few do REAL tire testing, ...but many have UNsubstantiated "OPINIONS".  In some instances, maybe a lot of instances, I wish I could share some teaching and riding.

More about remarks made by others, regarding their tire likes & dislikes:


a.  FEW street riders ever come even close to the potential of their tires, & fewer ever do strictly controlled testing. 

b.  Some ...well, actually MANY, reports on tires are wishful thinking.

c. Those whose background includes a lot of actual paved racetrack time have a strong tendency to report semi-race-performance as a comparison-evaluation on tires.  This is not what my testing is about, for YOU.  I am not going to compare a race-bike, with race tires, ridden hard, .....with hard riding on the street ...not even compare light racing.  My testing is for real-world riders for commuting & touring use, who may or may not, sometimes, or even often, be brisk and aggressive.    Be very cautious about who you listen to about tire performance, because riding briskly on public roads, is NOT the same as being on a racetrack trying to win a race (or, even just having a good time), where racing (usually) tires are well heated-up, stick & handle very differently in almost every respect, including braking, transition between modes, flickability, etc.    DO NOT let race-performance dictate YOUR tire purchases! ASK the reviewer, so-called-expert, etc., about his/her SPECIFIC testing details & COMPARISON METHODS.

10.  I tested tires on both asphalt roads (especially with various types of tar repair stripes, and washboard roads both of which also test suspension stiction); concrete paved roads as well as gravel/hard-pack; and, occasionally rather soft stuff (yes, on road tires).  I did REAL ACTUAL CONTROLLED TESTING.  I have racing experience both on/off road, on 2-wheelers & sidecar rigs (sport cars too).   I have available close-by my home some very specific roads that I have CONSISTENTLY used since 1973 for testing.  These offer a wide variety of surfaces & conditions.  I tested in below freezing temperatures, as well as warm Summers.  I made a point of trying to ride when it rains, because it does not rain very much here.  I even tested on somewhat icy and snowy roads.   When I first moved here I had a R75/5 for good weather/roads ...but I also had a "light weight" (for back then!) dirt bike, shod with knobbies, that I rode in the snow. It was great fun but physically a lot of exertion.  Would be too much for me now, so I no longer do that in the snow (although I still ride my sidecar rig in the snow ...lots of fun!).

11.  Up until maybe 8 or 10 years ago, some tire sizes were getting hard to find in proper INCH sizes.  While a number of the old sizes, such as 3.25-19, are available from several manufacturer's, some were not very commonly available.   An particular example is the 3.25-18 used on the R45 and R65.   HINT:  Try: http://www.durotire.com/    ....and click on CLASSIC (or similar word).  BUT, do, FIRST, check into the Heritage line of tires from Metzeler, & the Continental classic tires,  ...and the Bridgestone Accolade.

Many riders no longer use the classic inch sizes.  Recently, MANY inch-size tires are available again in various brands/models. Many are now trying the newer inch-sized tires. 
Several manufacturers now have tires specifically made & advertised for "Classic Bikes".  These tires are worthwhile looking into.  This advice INcludes the new radial tires designed for our classic bikes.  BTW...the old advice about not mixing up radials and bias ply tires on the same vehicle are, in MY OPINION, an old-wives tale, and do not much apply to MOST motorcyclists.  You are on your own here though.

All these things, including suspension changes, pressure changes, etc., can lead to a QUITE DIFFERENT ride from original stock configuration.  Most riders just want a good ride with good handling & good tire longevity & don't really care about the 'classic' feel & handling.  MANY have a lot of experience on other brands & models of bikes, & may want their Airhead to FEEL & HANDLE similarly, or 'just better', whatever THAT means to them.  LOTS OF VARIABLES.   It is DIFFICULT TO TEST TIRES for everyone. Think seriously about yourself, your abilities, your actual riding, TRY to KNOW what you like & want, & if you don't know ...well ...nothing says you cannot try a few different tires. But, 99% of you will not invest the $ to do short mileage testing/sale/buy/test.
 


Tire Pressures (and, rear tire wear)>>>>.....an important section in this article ...please read totally, and carefully!

MOST 'modern' tires on Airheads (perhaps to as late as 1985 and maybe even 1988) require considerably higher pressures than stated on the tag under the seat or in the owner's manual or in some tire manufacturer's literature.  BMW did better by the late eighties onward regarding tire pressure recommendations.  Failure to inflate to proper higher values on modern tires will result in poor handling; the bike may feel like the tires are trying to roll off the rim.  When you DO inflate to a higher value, the tire MIGHT feel skittery, until you are used to the improved handling. 

SOME STILL BELIEVE THE TIRE PRESSURE LISTED ON A TIRE SIDEWALL IS THE RECOMMENDED TIRE PRESSURE.  IT IS NOT.  IT IS A MAXIMUM TIRE PRESSURE, BASED ON WHATEVER STANDARDS THE MANUFACTURER USES FOR THE CARCASS, and other things, such as CONSTRUCTION & pressures versus industry classifications.  I treat tire pressures a bit more in-depth in   http://bmwmotorcycletech.info/TireRepair.htm  in a section near the bottom of that article. 

FOR MANY YEARS I have been telling people that the tire pressures printed in their owners booklet, & in various literature, & particularly so for BMW's prior-to-~~1985 models (after which, ~~,  tire pressure recommendations are more reasonable), are OFTEN MUCH TOO LOW ...for modern tires.

When the rear tire 'squares-off'; & some do this rather faster than others (dual-compound tires are better at not squaring off fast), handling can be poor in curves, particularly fast changing twisties.  INstability (wobbles) can be very apparent with a squared rear tire, if such problems happen.     See:   http://bmwmotorcycletech.info/instability.htm.   Some types of instabilities can be HIGHLY dangerous & not just annoying.  In some instances, when combined with, perhaps, an improperly adjusted steering head preload; & maybe, OR NOT, other things, such as saddlebags, backrest,  windscreen...etc.   ...you can SUDDENLY get a very bad wobble, at high speeds.  YES, I did just say that squared-off REAR tires can cause high speed wobbles!  That has been extensively PROVEN & you need not take my word for this! .....read the article.

At the end of this paragraph is a link to an AVON page with charts of recommended tire pressures.  I mostly agree with them.  This is one of the very few tire pressure guidelines that does not have lawyers telling the tire makers to recommend only what BMW (or other mfr) says in their literature WHICH PROBABLY IS NOT CORRECT FOR THE TIRE MAKER'S TIRES!   AVON MOTO HAS BEEN KEEPING THIS ARTICLE CURRENT, AND ADDED MOST BMW MODELS, INCLUDING AIRHEADS!   IMO THE PRESSURES ARE VERY CLOSE TO MY FINDINGS FROM TESTING! You might notice, even with a quick glance, that the guidelines don't have anything much or overly-specific to say about TYPES of tires.  That's because differences, unless for specialized purposes, are NOT ALL THAT PERTINENT.   You may notice that tire pressures are recommended that might be higher than in other tire makers literature, particularly if they use BRAND names for bikes.  That's another way of saying that lawyers have too much influence on many tire makers!    I HAVE FOUND NO OTHER HONEST REPORTING LIKE THIS.  BE SURE to click near the top to select BMW in the small box.

http://www.avonmoto.com/tech/tire-pressure-guidelines
 



Tires by brand & model:

HINTS: 
(1)  A TUBELESS tire that does NOT use steel strands in the tread is much more likely to have a LASTING on-road repair, by using sticky strings or internal patch.  This is particularly so if you are using such as the Stop'nGo mushroom type of plugs, which require a lot of reaming on tread area puncture holes on steel ply tires.   The Avon Roadriders, as ONE example, do NOT have steel plies.  Conversely, that makes them POSSIBLY more conducive to punctures.  All this is strictly speculation!  I am not knocking Stop'nGo, I carry their plugger kit with me!  I MAY run some puncture tests on tires if I live long enough!

(2)  If using metric tires in place of a front 3.25 inch standard stock size, use 90-90; or, if you must, 100-90.  Pre-1977 bikes need a wider fender mount for the wider 100-90 tire, 46-61-1-234-907, this is common to all brands for that size.  I suggest if using metric rear tire sizes on your early TWIN-SHOCK Airhead that was originally 4.00 x 18, that you use 110/90-18 and NOT 120/90-18 rear as it is not generally recommended by me for twin rear shocks Airheads models, especially the rear drum brake models with cast Snowflake wheels which are 2.50 inch width (The disc brake RS and RT are 2.75 width).


Avon:
ROADRIDER (AM26): This was the first 'new style' report of what I hope to do in the future: that is, highly detailed reporting.  I had, in the past, very limited mileage on the AM26.  I was then not fond of them in moderate to deep rain; nor on paint stripes, & did not particularly like the AM20/AM21 either.  Avon Roadriders (AM26) are moderately priced; DO, reportedly, for most, seem to get reasonable mileage, but some few have reported the opposite; but in at least two of those limited number of reports, they often rode on rough surface roads, probably sharp-edged chip-sealed roads, which wears tires fast.  However, wear on moderate chip sealed roads has also been seen to be rather excessive.  I do not consider them a pure mileage tire, but a handling tire with decent mileage.  Roadrider's have been reported with cracking, in the tread and next to the rim.  Many don't replace them just for cracking.  No reports of actual tire failure problems (AFAIK!).   Since I reported this earlier information, I have had the opportunity to put the AM26 tires through considerable additional testing SEVERAL TIMES...and a number of miles.  This is because my 'new-to-me' (1995 R100RT) bike came with them, with only a few thousand miles on the tires. Several years old. 
NO cracking at the time I purchased the motorcycle (read onwards....). This motorcycle is a MONOSHOCK, specifying a wider tire on the rear, than on early Airheads.  Metric size tubeless tires are specified by BMW, on stock BMW rims designed for tubeless tires.  These Avons are, therefore, being used as tubeless.  The wheels on this motorcycle were stock, as was the suspension (and in good condition). Standard equipment, with a few notable exceptions:  The BMW rear trunk that came with the motorcycle was NOT fitted.  A fairly tall backrest is fitted.   The stock windshield had been replaced by a Parabellum with a curved bottom design that allows air to flow at the bottom.  I cut the windshield to ~13 inches in height; quite low for this type of touring bike. That height is not optimum for weather & helmet top buffeting, but allows me the view & slightly sporty downward forward position I prefer, even on an RT, & even for my age; AND, gives better air flow into my top-of-helmet vent.   I am making these notes because all sorts of things AFFECT HANDLING.

Avon makes these tires in directional & bi-directional (Universal).  The tires I did the testing on were a 100/90-18 front bi-directional tire (stock size for the bike is 90/90-18), with the proper tire direction for the front, as marked on the carcass.  Using a 100/90 front is popular.  Rear was stock 120/90-18, single direction marked.  Rider weight 164, as ready to ride with helmet, jacket, etc.  Shortened windshield (15" much of the time, later 13" as noted). Tour bags (empty), Tour Rest, NO rear trunk fitted.  Always between 1/4 & 7/8 fuel tank level. Tires were 4 years old FRONT; 3-1/2 years old REAR.  Neither had truly visible cracking nor other deterioration in the beginning, just some faint tread tendency.   Rear tread still well rounded.   Tires had ~5000 miles by the time I did formal testing. 
It was nice weather for the tests (70's-80's F.).  I rode mostly on both smooth & slightly broken & cracked concrete & black asphalt.  I purposely did some freeway riding at low speeds (& up to 90 mph), specifically hunting-for & using rain grooves, at various speeds, straight ahead, and angularly.  I tested those grooves with my weight forward, as well as very considerably rearwards.   This bike does not use nor come with a steering dampener. FYI: I DO NOT DO TESTING WITH ANY DAMPERS TURNED ON (except sidecar rigs).  I began tests with the recommended pressures right from the BMW owners manual.  I did tests with various pressures.   I consulted with one person who had a similar bike, who weighs a LOT, and another who usually travels with his wife behind him.  It was from them that I got the psi for heavy loads, which was ~what I expected.

At first my bike felt especially twitchy to me, same, or more so, as previous tests.  I believe a modest amount of this was due to the one size oversize front tire, which causes the bike to have a somewhat extra tendency to 'fall into slow turns'. I did pressure change testing, & noticed the twitchiness no matter the pressures used.  That never completely disappeared.  It took me a while to get used to.  Direction changes happen nicely and quickly with low input from the rider.  This is the same as I have found with many, if not most, modern tires.   Handling over-all is light.  Braking is good.  BUT...these tires FEEL like not enough rubber is touching the road.    They feel like almost any reasonable tire pressure I tried was too high, but THEY REALLY DO STICK WELL ...except they are rather slippery on such as paint stripes.  While that is so for all tires, these were SLIGHTLY worse.   Because of these various things, I do NOT recommend using an oversize front tire, such as on my motorcycle.

Some serious testing, perhaps my last time at doing quite such highly aggressive testing, was done going both up & down a particular twisty mountain pass that was rather steep, but smooth, as the asphalt was recently paved within a couple of months (Luther Pass).  Quite a few runs were made to determine best tire pressures; corrected to cold values.  I repeated the final test on a later cool morning, setting the cool tire pressure to 32F, 36R; the factory recommended pressure.   OVER-ALL, A SURPRISE!!  These 1995 BMW factory recommended pressures worked well! ....for a good compromise of handling & comfort (BEST performance, pushing the tires rather hard, note my light weight,  was at 35 front & 39 rear, from cold).
   For a heavy rider and/or heavy loads, especially for touring, and most especially with two-up and at high speeds, I suggest 35F & 40-42 R.  Over-all, these tires work OK under all conditions so-far tested, subject to my comments.  I think if you need to fix a flat, that standard soft plugs as provided by Stop'nGo, for use in their special gun, would work well, & so would sticky strings, because there are no steel strands to cut the plug or string ....see earlier in this article.

The following caveats:
NO tread mileage tests ...may be quite some time before I report on that; so far, looks relatively decent but these WILL NOT be super-high mileage tires. The Roadrider REAR seems to have rather little squaring-off, at least at ~5000 miles, which is somewhat surprising. I will have more to say on that in the future. Seem fine on normal lightly wet roads, not yet tested in deeper water. Slippery on paint stripes, & BADLY so if the road is wet.  SAME FOR SOME TAR SNAKES.  NOT unusual for any tire.  Have not yet tested the tires on deeper gravel & dirt roads.  Were OK on hard pack with shallow gravel top surface.  These tires moderately track rain grooves; but NOT NEARLY as badly as straight ribbed front tires do.  
Due consideration should be given if you ride a LOT on rain-grooved roads. I fully tested these tires on dry rain grooves on several roads, including high-speed freeways, & on two separate occasions, on different roads; so: while they do follow rain grooves, especially so if the grooves are pronounced and not straight, it is mild to moderate, & probably will not overly annoy anyone.

August, 2016: The tires, both front and rear, are beginning to exhibit more noticeable tread cracking.  That is, at the bottom of the tread in the center to slightly to one side of center, there are cracks appearing.  The tire cords, if very thinly, are very faintly visible.  There is NO sidewall cracking, particularly inspected was the area near the rim metal.  The rear tire showed more cracking than the front, perhaps 3x more.   I will be watching this situation closely. I also have ridden someone else's Airhead, an early eighties RS, shod with the stock size equivalent tires, and the suspension, etc., on that bike was checked to be in good condition.  The tires were cracking AT THE RIM AREA.  No change in my ideas about handling.

November, 2016:
  Did 30 miles of stability testing. This mean level and fairly steep up and down asphalt-paved road, rather recently paved.  I did straight areas and areas with moderately tight twisties.  I purposely took my hands off the bars and tried to induce shakes and oscillations by hitting either end of the bars.  This was done in normal riding position, normal pressures, 50F temperatures, sunny.  The tires could be put into mild, correcting oscillations/shakes, at almost any speed from twenties to the highest test speed I did, ~70 mph.  Placing one or both hands on the bars instantly corrected the shakes/oscillations.   Conclusion:  for proper preload setting on the steering bearing, or even near it, stability was OK.   With weight to the rear of the passenger seat (that is, onto the rear rack, 20#), stability worsened to 'just acceptable'.   Over-all, this tire is OK, but those with rear weight and/or lots of WAVY rain grooves might not like it.

Bottom line:  good tire (cracking aside).  I prefer the Michelin Pilot Activ; and I haven't any experience on the new Continental Classic Attack's ...yet.  I think the Avon Roadrider's are worth the cost, which is somewhat LOWER than the Pilot Activ, etc. ...but the tread cracking is to be considered! The cracking is a potentially serious problem!   For years, as noted below, the Bridgestone S-11 (Spitfire) tires were ones I used for comparisons.  I think they FEEL more stable than the Avon RoadRider; even on rain grooves.  I still like the S-11 & perhaps prefer them for a high percentage of street riders ...all things considered (price, performance, mileage, handling and feel).    I am putting a NOT RECOMMENDED rating on these Avon RoadRider tires, primarily for cracking & possibly short life ...and this has been reported by others.

GRIPSTER AM24: 
For Dual-sport riders.  Has been around for a LONG TIME & it is a well-proven tire; fairly good street tire if a bit noisy, sticks WELL in cornering, quite stable & not bad in rain either.  Works pretty good in off-road gravel & hard pack, fair/poor in mud, & are, perhaps, a bit rough/hard feeling.  I suggest using about 31 psi front & 35 psi rear for all-around use.   These are possibly not quite as good as the Michelin Anakee for street and dirt.   The Continental TKC 80 is better than the Avon AM24 off-road.

DISTANZIA AM43/AM44: 
Is much more of a street tire, decent in the rain, only fair off-road, but fine for the street rider who ventures off the road on occasion.


NEITHER of these Avon tires would be my choice for a bit deeper or rougher off-road dual-sport work.  Both the Gripster & Distanzia are primarily paved road tires, with modest to OK off-road capability, the Distanzia having the edge for the street & life, at maybe 1/3rd more cost.  The Gripster is a quite decent tire for the person who is primarily a paved-road-rider, yet ventures off the road now & then, who may even be a bit aggressive off-road. The AM24 is a GOOD all-around tire & works well in anything but mud; keep in mind that usually only VERY aggressive tires work in mud.       See the Continental TKC80, below.


Bridgestone:

S-11 Spitfire.
Tested:  110 rear, both 90 and 100 fronts.  ONE of my old favorite ROAD tires, all things considered.  They are predictable & quite good for the $.  I first tried these MANY years ago on a SWB R75/5, & liked them immediately.  Predictable handling in all conditions, although like any true road tire, they are NOT for deeper soft stuff or mud.  Decent mileage & good grip on pavement.   One of the first, if not the first, dual-tread-compound construction, is part of how they get the performance (esp. mileage).  NOTE! ...it is my belief that these tires AGE a bit more rapidly than many others. The result is that they tend to get a bit slippery or skittery, more noticeable on wet roads when they GET OLD.  While this could be said for most all tires, these seemed a bit moreso. I don't recommend these tires if you don't put on some miles every year ...although they are "OK".  Not particularly great if you are a truly aggressive rider, especially considering the newer higher performance road tires, such as the new type classic radials.  My recommendation says "all things considered".  That means ALL things.   If you want a bit better handling in the wet, & perhaps a bit less aging, then consider the pricier BT45.    In the last dozen years or so, better tires have been available, but at some $$$.  I used my extensive experience on these S-11 tires as a COMPARISON guide.   For MOSTLY dry roads, for distance or local touring/cruising, these tires do fine, although I'd avoid being truly very aggressively pushing them to hard limits in slippery turns.

My 1984 R100RT got 10,600 miles on the last REAR S-11 tire.  The bike was mostly driven at maximum legal highway speeds (& higher!), but average aggressiveness.  The tire still showed tread that was usable, but it was down to almost 1/16".  A good tire for all paved roads, decent in rain by standards 15 years ago, & even OK for those that ride somewhat aggressively ...again, by older standards.   To make this clear ...these tires ARE much better than the original tires that BMW put on your older Airhead; and, they are nicely cheaper than many other tires. For those that do mostly highway riding, with occasional rides on gravel & hard pack, the S-11 are good because these dual-compound rear tires do not tend to flat-square quickly, although, like all tires, they likely will, eventually.  Squared-off rear tires can lead to high speed weaving & other instabilities, even dangerous types.  Again, note that this happens with ALL rear tires, but these tires DID NOT exhibit it very much.  This alone makes their value good, & considering the handling & mileage, a relative bargain. They handle WELL enough....AND PREDICTABLY.  For Mr. Average to a bit more aggressive Rider, I cannot fault the S-11. They have been available for a long time, and don't have any problems.

BT-45:
Another Bridgestone dual-compound tire.  Better than the above S-11 in wet conditions, maybe somewhat better in all conditions, but at a large $$ increase for the small improvement you get, so I do not think them worth the substantial extra cost over the S-11. You might.  Perform well, under all paved road conditions.  A bit better off-road, than the S-11. They do not feel the same as the S-11, probably due to the tread design & possibly an internal carcass change.  Good, over-all.   There are better tires today for the aggressive rider.

Accolade:
Front is ribbed:  I do not have any experience with these tires. Supposedly these can produce a more classic, original early BMW ride.

Cheng Shin: 
Chinese-made.  This brand used to have a bad reputation for problems.  That is NOT SO now.  These are now decent tires delivering OK performance, at a low price.  The 906 model is similar to the Metzeler Laser ME33.  It matches well with the 907.   Decent tire in both wet & dry.  I have not tested any other Cheng Shin tires.

Continental:   
TK 16, TK17.  Were NOT recommended.  Especially 120 size, which is much too wide for ANY dual-shock airhead.    Listed here only for those comments.  Very obsolete tire anyway.

TKH23 front & TKH24 rear are also called Continental BLITZ, are bias ply rayon construction, long life tires, available in 3.25H-19 front & 120/90H-18 rear. I cannot remember if that rear can be fit, it might have the too-wide fit problem as the TK17.  BUT, they make this tire in a 4.00-18 rear ...and it DOES fit.     Otherwise, decent tires, reasonably priced, can be run with or without tubes, and are rated tubeless. 

TKC70:  More paved-road than off-road.  Probably similar to the Metzeler Tourance, over-all.  If your riding is more off-road than paved, try the TKC80.  I have personally not ridden on the TKC70.

TKC 80:  This tire has been around for some time.  It is for dual-sport use & good on pavement besides off-road.    OK even in rather aggressive riding, although feels a bit squirrely to me, even considering the tread.   Limited sizes available?  Grips OK on pavement, on sand & gravel, dirt, even reasonable on mud!    A GOOD choice for those going off-road more often ...yet retains good performance on the street, FAIR/OK when wet, even "OK" on snow.  One of my favorite all-around dual-sport tires.
    It, perhaps surprisingly, corners good.  Does not last as long as the Metzeler Tourance.   This is not a great mileage tire for mixed use ...but was surely worth it for heavy adventure bikes, like the BMW GS line.  Tossup as to whether you'd like it over the Avon AM24 Gripsters, but I DO.  The TKC 80 is fairly quiet, inspires confidence in how it FEELS.   I think MOST riders, no matter the model of BMW, will like this tire, even if you are a street rider but do maybe half your riding truly off-road. If you want all-around performance in a tire that will be 'capable of any surface', even some mud, THIS IS THE ONE.   Original equipment on some BMW models.  If you like the TKC80, you might also want to try the TrailAttack.  You also may want to look at what I say about the Kenda K784.  I have NO experience on the TrailAttack, & welcome comments.   For sure, try the Avon AM24 Gripster, to compare to the Continental TKC 80.  You might prefer the Michelin Anakee-Wild tire.
Drawbacks:  Expensive.  Tread too aggressive for "mostly" street riding. Tread blocks wear weirdly sometimes.



RB2/K112 (also TK22): 
Original types used on the OLDEST Airheads as ORIGINAL equipment.   I have not ridden on any in many years; I always disliked the way they followed rain grooves ...but they do ...or at least did ...offer the classic BMW soft ride.  Mileage and handling is good if used with original 'high-speeds, two-up' tire pressure settings.  I might try testing some of the new modern versions as I have heard the rubber compound is improved since Continental re-started production some time ago on these.    Owners of early Airheads that came with the 3.25-19 front & 4.00-18 rear tires as stock sizes, should try a set of these Continental tires if they want the classic ride AND LOOK.  You won't get exactly that classic ride if you have a modified suspension.  The originals were "OK" but not for true performance riders, especially if you are fairly aggressive, and considering the newer designs available now.  Note:  I don't purchase Continental tires myself due to how they treated my shop when Continental had a bad batch of tires, decades ago.  But, I do NOT, in the slightest, want to discourage YOU from trying these tires, as you may love them.    If you intend to ride on classic tires, I also suggest the Metzeler tires like the ME11, etc.  Accolade tires??  BMW installed Metzelers in the old models/sizes, besides Continental's.

This is the Continental RB2 (front):



Classic Attack Radial (Conti Attack Classic Radial):
This is a new design from Continental. Continental says that they specifically designed this tire, A RADIAL 0 type, to enhance & sharpen the handling of older classic bikes which were originally designed for bias-ply tires.   I have not yet tested these tires.  From a look at the tread pattern, I think the tires MIGHT NOT track rain grooves, & should feel fine.  The tire is supposedly fairly high mileage with excellent grip & fast break-in.  The V-rated tire is available only in metric sizes (??).  The 100/90R19 57V TL, a front tire, is expensive, although discounts may be available. That tire, like all of that size, will probably not fit earliest Airheads without the proper later fender brace, 46-61-1-234-907 from the 1977-1980 /7 series.  Probably will need the later fender too. The other usable metric sizes are a 90/90 in 18 inch size for later airheads, and available is also a 110/90R18 61V TL & 120/90R18 5 65V TL, these two are designed for rear use.  The 110 is likely the BETTER choice over the 120.  NOTE the load rating on these tires, compare to your previous and other tires.  Tubeless construction. If used with tubes, you should reduce the speed rating by one step. That's FINE for Airheads, who hardly usually need more than an H rating, let alone an S or V.   Some riders who have tried these LOVE THEM.  As noted, no personal testing information yet. Tom Cutter reported that these type tires were easy to R/R, provided a comfortable ride, were stable, and had a nice feeling.     ... somewhat expensive.  Other sizes may become available.  I am looking forward to comparing these tires to Michelin Pilot Active & Avon RoadRider.

Dunlop:
Vintage K70 front, 3.25H-19; K70 rear, 4.00H18/.        No comments.

Somewhat similar in some respects:  Dunlop F11 front 100/90H-19; use it with a K627 rear 110-90H-18.  Reasonably OK, obsolete now.

K491-Elite II: This was a Premium-cost tire, premium priced and a VERY long lasting VERY high mileage tire.   Pretty fair wet handling for such a long lasting tire, and good on rain grooves and reasonable in rain.  90-19 or 100-90 front; 110/90-18 or 120/90-18 rear.   It was a classic high mileage tire when available. Some loved them for LD touring on both lighter and heavier bikes.   My tests agreed.

TrailMax Dual-Sport:  can't recommend these; lousy off-road.

D606:  This is a good mixed use tire, for tarmac AND off-road.  It is priced in the lower area, and is good on road and off-road ...with an emphasis for off-road.  My limited testing found some high speed instability, but I did not have time to test pressure changes nor loading in that regard.   Good performance for the cost.   I think the Michelin T63 is better.   GOOD TIRE ...some may like it over the Conti TKC80.

Heindenau: 
K60 Scout tire is nearly as aggressive as the Continental TKC80, but costs a LOT less. You may really like them, over-all. LIMITED experience.
   The Heindenau off-road tires seem to be longer lasting, harder material, but not as good, in my LIMITED testing, as the TKC80, and probably not at all compared to the new Michelin Anakee-Wild.

Kenda:
K784 Big Block.  So-so on pavement, pretty good off-road, even good in mud.  Wears relatively fast ...to be expected for good off-road and even usable in mud type tire.        NO personal experience.

Maxxis:
C6011 is good, not sure if it is available in the 18 inch now.  See Cheng Shin comments.

Metzeler: (see Continental, RB2/K112, for comments regarding the Metzeler ME11, and Heritage tires)
***UPDATE, November 2015:    Metzeler has moved some of its existing tires & some new versions of old types, into a new category, called the Heritage series.    While this includes the Lasertec, it also includes some classic Metzeler tires, mostly updated with newer compounds and manufacturing.  This should bring better handling & longer life, but I have NO testing experience on them.  The tires will mostly have the original tread profiles & appearance.    These tires are the Perfect ME11 front; Perfect ME77; Block C.

ME33 Laser:
Both standard & the low profile metric.   I recommend the 3.25 (maybe OK, you choice, 3.50 front).   If you have gone to an oversize rear, use the oversize front.   This tire will SEEM to follow some types of rain grooves, but NOT as badly as a ribbed front tire.  You can use this front tire with many other rear types.   Decent in the rain, good dry grip (LIKELY WAY BEYOND your bike's capabilities).  For mileage, you can expect decent, if not outstanding values.  Some tendency, sometimes, to cupping.   The ME33 tread design was unique when introduced & has been copied by others.  It has a lighter faster turning 'feel'.  There was a K compound version that was for racing.  Both NLA, I think.   This tire will tend to scallop if shocks are poor, but still handle OK.

Lasertec:
I do not like this tire.  NOT for the less-aggressive rider and is twitchy, giving an unstable feeling.   Aggressive riders might want to try it. This tire does NOT feel like the ME33 Laser to me.   The tires have been reported as inconsistent in manufacture.  That may be so. 
They tend to follow rain grooves ...likely due to its single circumference groove or multiple wiggle type grooves) in the center of the tire.  If you don't have grooved highways, or don't mind the (not awful) instability, then you MIGHT like this tire.  I was surprised by the twitchiness, & while different, I compared its twitchy feeling to the Avon RoadRider. The twitchiness may be partly a "less-rubber-on-the-road" FEELING.  I did NOT do tire pressure testing.  NOTE that many modern tires have some light handling qualities, which I call twitchiness.  It DOES stick "OK", corners nicely; gives "some" confidence in tight twisties.   This tire should match up with many of Metzeler's other tires.   I just did not like the tire much.

ME55: 
An old favorite for some.  I never liked this tire, although it gave a reasonable compromise on handling & mileage. I preferred the ME88 for the rear.


ME88:  
Front & rear versions.  A mileage tire, reasonably good handling; one of my old favorites for use front & rear for TOURING.  Interestingly, this tire also worked well as a rear with ME 33 Laser front, for more aggressive paved road riding.  I have tested ONLY those made in Germany.    AFAIK, discontinued ...unfortunately.

ME880: 
NO personal tests yet; no trustworthy reports yet either.

Tourance: 
OK on the street, "fair" on gravel and hard-pack dirt. The Michelin Anakee is probably better all-around, by a bit, wet and dry, for dual-sport.  The Continental TKC70 is roughly the same, performance-wise, as the Tourance.   Tourances are NOT good in any sort of mud.

Enduro tires: 
Metzeler has a selection of these tube type tires to fit older airheads.  The Enduro 3 (Sahara or Sahara 3) is a good one for mixed on-off road.  It is pricey.  Watch the WIDTH ...Enduro tires may be MUCH wider than their sidewall-printed size might lead you to believe; thus may not fit on twin-shock models, due to swing arm clearance problems.  I use to use the Sahara 3 for my rear tire on the sidecar rig in the Winter; mainly because I got several cheaply.  Nearly every motorcycle tire manufacturer has its own enduro tires.

MCE Karoo: 
These are good GS type tires for off-road, fairly decent on pavement. I suggest you don't mix other types on the same bike.  For pavement use, especially if the weather is cold, let them warm up before getting aggressive with them.    Many equate these tires with the Continental TKC80, I think them only somewhat similar.  There is now a Karoo 3 ...no information nor testing by me.

Michelin:  (All of Michelin's tires seem well-made, well-balanced, high quality)......>> 

Macadam 50 & 50e.  100/90-19 & 3.25-19 front; 110/90-18; 4.00-18; 120/90-18.  Some really liked these.  I don't have enough miles on them to say much. 

The Pilot Activ replaces the Macadam.   The Pilot Activ SEEMS, in LIMITED testing by me, to be better for wet streets, handles better, reports say long life; may be comparable to the Bridgestone BT45, per SOME.  I, however, think it rather SUPERIOR to the BT45.  In 2013 I installed a rear Pilot Activ 4.00H18 on the REAR of my 84R100RT & did mild testing.  The front was a 3/4 worn Bridgestone S-11.  I intended to later install a front 3.25 H19 Pilot Activ, & do testing all over again, but no longer have the bike.   The REAR Pilot Activ worked nicely with the very different tread profile on the front Bridgestone, and with different pressures too.   Previous tests on someone else's bike, with BOTH tires being Pilot Activ's, were not extensive enough for me to say much more until Summer of 2015 .... when I had the opportunity to test ride a WELL-MAINTAINED R100RS with BOTH front & rear tires being Pilot Activ's, with less than 2000 miles on them.   I asked the owner to let me ride the bike & test the tires.  Luckily, it was someone who has ridden with me before during tire testing & he said yes. I did a fairly thorough testing, but NO testing was done in soft stuff, nor on wet roads (unavailable at the time, but WAS done later on).  I did some pressure testing.  I first rode locally, then did three passes, & then on a nicely repaved but broken-in asphalt road with several substantial twisties & one slow speed tight turn, through which I very aggressively rode.  On the way home, I did a higher speed highway & made a detour onto a freeway with a constantly tightening radius downhill entrance.  The initial part of the freeway after the entrance is my favorite area to test for rain groove handling.  

I thought it a good idea to somehow repay the owner (especially considering the amount of rubber I wore off!), & so I treated him to a very nice dinner.  I did 93 miles on them.  I was VERY IMPRESSED with these tires.  I have no idea what mileage would be obtained.      MY NEXT SET OF TIRES MAY BE THESE FOR MY OWN BIKE (or, one of the new radials for classic bikes).     I think the Pilot Activ one of the best handling of the modern tires for street usage.   I think most average riders will prefer 33 front and 38 rear pressure, with heavier riders, higher speeds, and maybe a passenger, needing several more pounds in both.

I had a miserable time trying to mount the Pilot Activ 4.00H18 to the 1984 R100RT rear snowflake wheel.  One side went to the rim bead area OK, the other VERY difficult to get concentricity.  I am NOT the only person to have this problem.  Because of this, I modified my air equipment AGAIN, & then it went on OK, withOUT excessive pressure too!  I found it critical for the rim/bead area to be clean/smooth, I even polished it ...& used LOTS of real tire lube. I added the new inflating information to my tire repair article, primarily an opening-up of the chuck, removing the valve in the tube, etc., to increase FLOW RATE. See: http://bmwmotorcycletech.info/tirerepair.htm.   This tire is very stiff in the sidewalls, even the tread.  Do NOT be discouraged by these remarks. This tire has a very well-made bead edge, which should offer better sealing on a tubeless rim than many others ...but a tubeless rim & a tube type rim do NOT have the same shape for the bead area ...the angle can be 9 different in some cases.   For those who use a tube type rim as tubeless, I think this tire will do better than many others in the instance of an air leak or flat.  This is speculation on my part.  Such usage is not recommended by many.  There IS an article on this website about such usage.     http://bmwmotorcycletech.info/section6.htm

Standard Michelin Butyl tire tubes for my testing.

Anakee3:
The Anakee 3 is different from the Anakee 2.  The 3 is for mixed on and off road, seems pretty good all-around until you get into mud, where it's poor.  Emphasis is on pavement riding.  EXPENSIVE.   May be difficult to mount?  Competition for these tires are the Continental Trail Attack, the Avon Distanzia, and Metzeler's Tourance.  In general, the Anakee line of tires is competent.  I have not had a chance to try the Anakee-Wild; only seen reports on these radials.   Some think these are THE best on/off road tires available ...with good mileage too.  But, they make noise.  The rear tire on these seems unique in tread design, and seems to work well.

T-63: 
For more aggressive off-road riders, handle decently on dry pavement (not too bad on wet roads either); probably one of the best buys for mixed use (dual-sport, with a fair amount of emphasis towards off-road).  The T63 is a good tire.   A trusted friend told me about this tire, & how he, on a bike loaded with luggage & his girlfriend on the rear of the seat, practically melted the tire from very high speeds, in Arizona, in exceptionally hot weather on a very hot black asphalt road.  I went out of my way to test this tire on someone's bike.    It is less expensive than much of its competition.  This tire has an aggressive enduro tread, so unless you do some off-roading, don't get it.   This is NOT the tire for quite heavy loads at quite high speeds, coupled with very hot asphalt.  In fact, I can't recommend any Enduro or knobby tire for that.  I have ridden 78 miles on an Airhead equipped with these.  My opinion matches someone else's, who rides aggressively.   While the tread does look aggressive, the tire is somewhat milder than it looks.  I do not know about expected mileage life, but I think the tire worth the modest cost.



OVER-ALL, I am IMPRESSED with the Michelin brand of tires.  (Even for my SUV!)


Pirelli: 
Scorpion:  Not recommended for GS.   I have NO miles on them.  Some reports say they exhibit wobbling if mixed with other tires, but I have no definitive information.

Sport Demon:  reportedly will change handling for the worse AFTER some miles are on them.  NO personal experience.


Shinko:
NO PERSONAL aggressive testing yet. One report (from someone whose riding skills are good & can ride hard enough to test tires reasonably well) likes these, & compares them to vastly more expensive tires.


The "everything else" section of this long article:

1A.  Some folks have trouble understanding tires sizes.  On metric tires the first number is the width in mm on a nominal width rim, the second number is the aspect ratio of the sidewall to tire height.  Metric sizes and inch sizes are not exact equivalents.  USUALLY a 3.25" size as originally specified can be substituted by a 90 metric (often coded as MJ); a 3.50" by a 100 metric (MM); a 3.75 or 4.00 by a 110 metric (MN or MP); and a 4.25 or 4.50 by a 120 (or MR).

There WILL BE handling differences if you do not use the originally specified size of tires.   Those that have heavy loads may want ONE size oversize tires.   It may behoove you to look into the load carrying capability of your proposed new tires ...usually molded/printed on the sidewall. SOMEtimes a larger tire is rated for a LOWER load.   Using a stock rear tire, let us say 4.00-18, with a substantially oversize front tire, is not the best combination, as the bike will PROBABLY have a tendency to fall into turns a bit; but I have NOT found that too excessive if not going too big. One of the problems is not just that the oversize tire is wider, measured sidewall to sidewall ....but, that the PROFILE of the ROUNDED TREAD is DIFFERENT, and handling is affected.    As I noted; sometimes an oversize tire will have LESS load capacity, and you may have to look at the manufacturer's technical data to find this out, especially if wanting actual load numbers ...rather than the tire sidewall information.  

I have very limited information on using 80 profile tires on Airheads.
Some seem very usable on Monolever or Paralever bikes.  Aspect ratios of 80% will NOT always work on early twin-shock Airheads.  It is often a matter of the sidewall width, not just other fitment problems.   The fitting problem is almost always only with the twin rear shock models, due to swing arm clearance, and also sometimes with disc brake stay arm interference (RS, RT, some S).  Brake stay interference also happens with twin shock Airheads.  Both swing arm clearance and brake stay clearance problems ARE usually easy to deal with.  Most of the early Airheads came with inch size tires: 3.25 x 19 inch front tire and 4.00 x 18 inch rear tire.   For some time, in the recent past, FEW tires were made in those sizes, but availability has now very considerably improved.   In general, these old sizes were in what, today, is called a 90 profile.  NOTE that the old Airheads (except G/S) did not come with enduro tires, and I mention this because most enduro tires in 4.00 x 18 will be VASTLY wider than a 4.00 x 18 paved road type of tire.  An enduro tire may well NOT fit in the slightest on twin shock Airheads, not enough room between tire and driveshaft housing.  This is particularly so on those before 1981.  These can have a wider right side of rear wheel spacer installed, and BMW even sells such, but that may not help nearly enough.  Very early Airheads could even have fitment problems with 110 size in the rear. In some instances SOME 120 will fit the later rear; BUT, sometimes (pre-1981 for instance) one has to get the wider 10.7 mm spacer for the right side of the rear hub ...BMW part number 36-31-2-301-737.   That spacer change has been needed sometimes for 110, but not often; more often for 120 (even for early eighties twin shock models).   Stock was 9.2 mm, 36-31-4-038-142.  The spacers are VERY easy to install, and do NOT affect bearing preload.  A few 120 rear tires fit rather tightly on drum brake models; that is, the wheel with tire mounted to it is a bit difficult to install, and deflating it is needed.  NOTE:  BMW uses 'top hat spacers', or call them brimmed spacers, at various places in the bikes.  You will find them at the swing arm sides, and the wheels.  One top hat spacer, 36-31-230-322, 12.9 mm wide, 32 mm hat, has been sometimes used to space the rear wheel to the left even more than the 10.7 BMW sells specifically for that purpose.  That spacer is 12.9 mm wide, and the hat is nearly 32 mm in diameter.   I would not try to move the wheel too far to the left, to accommodate a wide rear tire ...this is especially so on the earliest Airheads (/5 era) where the splines are narrower.

1B.   Spacers, tire sizes, and also rear spoked wheel changes:
For the front tire, which came as a 3.25 x 19 (and in some cases, like the R65, 18"), you can use a 90/90 metric tire and also usually go to 3.50 x 19 or metric 100/90, but you might have to use a later seventies fender mount. More much later in this article on that.   A 90/90 or even 100/90 on the front, and a 110/90 on the rear is very common and USUALLY WORKS WELL on Airheads, keeping good handling.

The part number used by BMW for some of the top hat spacers at the swing arm bearings is different than the almost exactly the same 9.2 mm part used at the wheel bearings.   They are interchangeably usable!

BMW modified the REAR WIRE SPOKED wheels for extra clearance, and this was done in the /5 days, as well as the ST and G/S days, and it was done by offsetting the spokes; details elsewhere's on this site.  While many think that the ST and G/S 3 mm offset change came when the REAR wheel went to a 2.50 from a 1.85 size, this is not so, it was later on ...after that change.

2.  The rear fender can be modified, hardly shows, makes tire changes easier.  htttp://bmwmotorcycletech.info/RearFenderMod.jpg for a photo.

3.  The BMW tube-type snowflake wheels are "WM2" in rim SHAPE.  Other articles of mine treat the use of tubeless tires withOUT tubes. Click here for that link,
http://bmwmotorcycletech.info/section6.htmIt is almost always OK to install a tubeless tire WITH tube into a tubeless wheel ...but mentally reduce the speed rating by one actual speed level grade, due to heat buildup with tube use.  The H rating is an anomaly, so don't just reduce by one letter.

4.  Try not to purchase tires more than THREE years old.  Date codes are on the sidewall, showing week of the year & the year.

5.  The maximum inflation pressure shown on the sidewall is for normal use as a MAXIMUM riding pressure.  It is not the recommended riding pressure, nor is it the inflation needed to seat a bead, which is quite often higher, just how much higher is subject to safety concerns.  For installing tires I don't go over 60 psi & try to stay at 50 psi, and use lots of REAL tire lube.  Generally the manufacturers will allow up to 50% over the sidewall printed pressure for mounting.   Be cautious because if a rim explodes you can be very seriously injured.  THE secrets to seating a tire bead properly are to have the RIM edge and bead area CLEAN and VERY SMOOTH, use LOTS OF REAL TIRE LUBE and have the tire and wheel (and tube if used ) truly hot from being in the sun!  REMOVE THE VALVE CORE ....AND ALSO REMOVE THE TIP IN THE air compressor's HOSE CHUCK.   USE A 125+ PSI 3 GALLON+ TANK ON THE COMPRESSOR & large inner bore size fittings & hose.    Be ready to quickly open any valve in the compressor-to-tire circuit.  ALL THIS SO THE INRUSH OF AIR IS FAST.  YES, the SPEED of the air inflation is a BIG secret!  Even so, an occasional tire will prove to be difficult.

6.  NEW tires are VERY slippery!  Allow 20-50 miles to scrub them off.  I first thoroughly brush the tires with a fairly strong detergent and hot water mixture and then flush them .... before riding on them.  I use a stiff bristled old-fashioned floor scrubbing brush.

7.  Continuous speed rating is marked on the tire, usually as part of the number/letters of the tire size.  Tires with deeper tread from the same manufacturer and same model of tire MAY wear longer, sometimes they do not.  Deeper tread tires are generally rated lower in speed, and usually are the better buy for touring.    If you do not ride at warp speeds, an H rated tire may be a much better buy than a V rated, as an example.   MAY is the word here.  Sometimes the only difference is TREAD depth ....the HIGHER speed-rated tire having a LESS deep tread.   This is not universally so.  A higher rated tire is NOT AT ALL necessarily a better tire ...for YOU!

Here is a chart of what the letters mean.  Remember, if you install a tube in a tire marked tubeless, reduce a true grade.  That is easy to see on the chart (except for the H rated tire which should be considered to be in-between U and V, and one step in practicality is a drop to S or T ratings).  Motorcycle tires have had for some time a LOAD index coding, something like 81H.   Motorcycle tires may eventually get the standard car tire coding of alphabet letters for wear and heat.  If you pack heavily, perhaps you weigh a lot, and you have a passenger ...pay attention to the manufacturer's published information on loading allowed.  Load carrying ratings for the tire are NOT the same as the motorcycle manufacturer's MOTORCYCLE load carrying rating.  Consider both.  

TL means tubeless ...does NOT mean you MUST run it tubeless.   - means bias ply.  R means radial; B means bias belted.  A FEW tires marked tubeless should not be used with tubes.  Ask, and look at the sidewall printing too.

LETTER Km/hr Mph
B 50 31
C 60 37
D 65 40
E 70 44
F 80 50
G 90 56
H 210 130
J 100 62
K 110 68
L 120 75
M 130 81
N 140 87
P 150 93
Q 160 100
R 170 106
S 180 112
T 190 118
U 200 124
V 240+ 149
W 270 168
Y 300 186
Z & ZR
group
  over 149
Some V, VR,
may be rated
over 149 Mph.

(W) is rated over 168 mph.

Y is rated at 186 mph.

(y) is rated at over 186 mph

   


8.  Tire direction:
Sometimes motorcycle riders or sidecarists will use a tire designed for rear use, on the front.  Some tires are even bi-directional, & maybe with two markings for direction, depending on if to be used for front or rear.

9.  WARNING!!!   For sidecarists, 16 inch rims CAN be used for passenger car tires OR motorcycle tires (if rim width and area to the safety bead, if any, is proper, or at least reasonable).  Do NOT generally use or try to install, a 15 inch m/c tire on a 15 inch car rim, nor 15 inch car tire on a 15 inch motorcycle rated rim.   You MAY be able to use a 15" car tire if the motorcycle rim is skimmed on a lathe or the car tire is a quite small one. ***PLEASE HEED THESE WARNINGS, and here is why:

15 inch car tires and 15 inch motorcycle rims are NOT the same diameter!   16 and 17 inch seem OK.  If you insist on putting a 15" car tire onto a 15" motorcycle wheel, the smallest tires may work OK, the larger ones are definitely dangerous. YOU CAN HAVE A CATASTROPHIC FAILURE!  Some sidecar manufacturer's use 15" car type rims.  NOTE that tire rim bead area is wider, from inside rim edge to the safety bead (if any), for CAR wheels.  This can create safety problems......

If you are using any combination of car rim with motorcycle tire, or motorcycle tire with car rim, there are some nerdy details you need to know; this link is a long read, but has some pearls of wisdom regarding use of those combinations:  http://www.goldwingfacts.com/forums/10-reference-faq-forum/400426-design-differences-between-car-motorcycle-rim-tire.html

10.  There ARE reasons to NOT screw the tube valve stem nut to the OUTSIDE of the rim.  Doing so gives no allowance for tube movement if you have a puncture or other leak & if the tire rotates on the rim some. Conversely, if the tube seals to the rim too well, it can trap air from tube to rim, allowing tube chafing.  Purpose of the tube nut is to help DURING installation of the tube; it can be discarded, or run up to the cap, after the mounting is done.  These ARE NOT just my ideas!   I can quote from tire manufacturer's manuals.  BMW has bulletins on these valve nuts, & one SI gave an additional reason to have it up against the cap, that was that improper inflation could cause the tube to be weakened at the valve stem & if the nut was at the rim & not the cap, the stem could suddenly disastrously tear out.  What BMW did not say, was that this comes from very low inflation AND over-inflation during seating of the tire. My tire repair article   http://bmwmotorcycletech.info/tirerepair.htm  has a lot more information on using the nuts, concave washers, valve insertion tools, etc.

11.  Inflation is usually in psi (pounds per square inch), but some tires and/or literature list pressures in BARS.  Bar means BARometric pressure, one Bar is atmospheric pressure, ~ 15 psi.  Manufacturer's, such as Metzeler, used to have in their technical engineering books, information, that during mounting, the maximum inflation pressure (DO use plenty of tire lube!!) was 150% of the tire sidewall printed value.    Manufacturer's are getting increasingly lawsuit conscious for products sold in the USA ...and many now say not to exceed the sidewall printed value, or 20% or some such.  Because 150% can be interpreted by some idiots to be 150% on top of the original pressure, some manufacturer's changed wording to say 50% increase over maximum sidewall-printed pressure. You are on your own.  I do not go over 50 psi unless I am forced to, and it is very rare indeed that I go to 60 psi on a motorcycle type tire.  This is NOT an OK for YOU to do that!  An exploding rim can kill you. However, I believe 50% over the maximum pressure as molded into the sidewall of the tire is  A SAFE LIMIT (assuming a good rim).  Seating of modern stiff-sidewall-bead-area tires onto the rim is usually THE problem seen.   Prepare the rim by cleaning the rim, and if it is not VERY smooth, on the outer edge, and the side area, sandpaper it SMOOTH. USE LOTS OF TIRE LUBE on the bead area of the rim and the tire bead area.  Have the tube and tire hot from being in sunlight for a considerable time, almost too hot to touch with bare hands is nice.  MIND the previous hints about using a modified chuck, no Schrader valve in the valve stem, & lots of lubricant ...really does works well.    read:   http://bmwmotorcycletech.info/tirerepair.htm ....completely.

An old "Rule of Thumb" says that after a considerable number of miles, the cold temperature pressure in a tire should have risen to ~6 or even 8% higher when the tire is hot.  That is generally true, but not all types of tires seem to conform, particularly some belted & radial types. Still, it can be a useful idea.   Where this idea came from is actually the manufacturers of tires.  If the pressure is too low, the tire will flex more, creating more heat;  if pressure is too high, the tire will not heat enough.  Proper tire temperature enables the tire to work as designed.   Tires require the correct pressure for handling & life, etc.  Sometimes someone will ask me about the actual tire temperature.  Road tires are designed to run at ~130C at the contact point.  That is VERY HOT.  That was NOT a typo, it IS degrees Centigrade. That contact point cools off VERY rapidly when you come to a stop, so you can pretty much forget about trying to measure it; particularly with a non-contact meter  that many seem to own.  They do not respond well/accurately to black tires.  A real nerd would get the temperature from the manufacturer, and affix a special temperature meter to the bike, and STILL not get accurate information!  One could, if super-nerdy, put a sensor into the tread, with a teensy little transmitter.

Many TIRE manufacturer's used to tell you the REAL tire pressure to use or try with their tires.  Lawyers probably got involved. Most literature now just shows the motorcycle manufacturer's recommendation ...which may be too low for old Airheads and modern tires.  Generally BMW recommendations are pretty much correct on the single sided rear end Airheads (with some caution for the ST and G/S) & usually any BMW motorcycle from ~1985 or maybe from 1988; ...and NOT correct, seriously not, for modern tires on pre-~1980.  BMW had recommended tire pressures on a label someplace under the seat & in the owner's manual.  Some later BMW literature upped some of the old pressures to SOLO 32-34 psi, both front & rear.  Those  pressures are STILL LIKELY NOT correct for YOUR riding, tires, conditions.   I have found almost NO tires that should have 32 psi in the rear!  Modern tires NEED higher pressures:  33-36 front; 38-42 rear.

12. Airheads came with a number of different rim WIDTHS and TWO GENERAL SHAPES, & one special shape.  BMW used the WM2 rim up until they installed tubeless tires, not officially OK with tubeless tires withOUT tubes.  Many arguments abound about this subject.  The WM2 rim does NOT have the 5 degree increased angle of the flat area inside and the side area ...all of which the tire bead rest against.   You are ON YOUR OWN if you fit without a tube, in a snowflake wheel designed for tubes.   Rim width and tire size fitted must be within a range of values in order to fit into the fender/brace/etc; and swing arm on the twin shock models.  If a tire is considerably too wide for the rim, the tire will tend to roll sideways on the rim itself, in turns, making for lousy handling.   EVERY tire manufacturer has a recommended range of rim sizes for each model and size of tire.  Those recommendations ARE correct.     Early /5 rims were 1.85" on front AND rear.  Later /5 bikes had 2.15" rear rims.  The 1.85" front rim was carried along right up to 1984 on most models.  The R80G/S had the narrow 1.85 front rim, and early ones the 2.15 rear, then came a 2.50 rear.  The R80 G/S had a 21" front wheel.  Some of the bikes came with a 2.75" rear rim ...this was on the 1978-84 RS, R100S; and 79-84 RT with disc brake rears; the drum brake rear bikes in these groups were generally 2.50".   With the Monolever and Paralever bikes, things changed with the rims again, with a new rim design, for tubeless tires withOUT tubes, etc.  An EXTENSIVE article on using various rims as tubeless, etc., is HERE:     http://bmwmotorcycletech.info/section6.htm

13.  Some have a hard time getting a pressure gauge onto the valve stems of the snowflake rims.  There is a 90 degree stem adapter available from BMW, I don't recommend its permanent use though. FRANKLY I don't use them at any time.  71-11-1-239-258.    Any of the stock type, 45 or 90 degree head pressure gauges are OK ....Consider checking their calibration once in awhile. 

For other purposes than difficulty with using a gauge, BMW also has a steel, chromed, straight valve stem, for use with tubeless (and for snowflake conversions, but this is NOT officially approved), it is about $4 from BMW ...and is available elsewhere's cheaper.  You cannot get a good seal with the stem, unless the inside of the rim has a flat milled place for that valve stem. The BMW number is 36-32-1-452-748 ...and this part is vastly nicer than a typical small car or yard vehicle all rubber stem. 

14.  Most flats/punctures are on rear tires.  MANY can be avoided ...by simply putting a wide and fairly LONG (tall) mudflap onto the FRONT fender, the closer to the ground the better.   Nice looking ones are available.   You may have to drill some holes, use screws, washers, nuts.   What this flap HELPS to do (theory anyway) is to deflect road garbage that would otherwise being thrown backwards, perhaps standing the debris upright ...and into the path of the rear tire.   Hence, the type that hangs down the furthest is desirable.  The truth is a mixture of that, and the fact that the REAR tire provides the tread-distortion of acceleration and engine braking and thus has much higher contact forces with anything on the road.

15.  Tire markings:
Tire sidewalls have a lot of information.   One area shows the manufacturing DATE.  On earlier tires, prior to year 2000, there were THREE digits... first two digits meaning the WEEK of the year, and a third digit for the year.  In the 1990's, there was a small triangle to identify that it was made in the 1990's.    Sometime during the 2000 year all manufacturer's changed to the 4 digit system, the first two digits being the WEEK of the year, and the last two digits being the YEAR.   If the tire code was 0455 or 455, you know the tire was manufactured in the 45th week of a year ending in 5 (but it had to be 1995, if the triangle preceded).   The reason only three digits was originally used was that the bureaucrats thought that tires would not likely be in service for over 10 years.

There is additional coding you may be interested in. There will be something like this:    DOT ENYO VLK 1704.   What you MAY be interested in is the two letters after DOT, in this example, EN.  These can be looked up at http://www.harriger.com   to find out what factory (China?) they were made in.  I have PURPOSELY not listed the exact URL for the specific PAGE in that website, as INTERNAL links do not properly relate to outside full URL's. 

There is a longer DOT code in use now.  The DOT coding begins by some letters and numbers. The first two letters identify the factory.  The list is at: www.harriger.com/tiremakers.htm.   The last 4 digits are the week and year, as before. NOTE that while DOT regulations mandate information on both sides of the sidewalls, you may have to look in two places and on both sides for the ENTIRE identification numbers & letters.   The original reason this was done was, supposedly, to reduce problems with the manufacturing and mould interference.  

16.  Recommended and NOT recommended tire vendors.   This section is not kept-up to-date.
a.  NOT recommended:  MAW   also known as Motorcycle Accessory Warehouse.
b.  Below, OK; but pay attention to shipping charges, sometimes if you buy TWO tires shipping is free.  Pay attention to date codes. 

Americanmototire.com

Motorcycle Superstore, Medford, Oregon.  Cheaper if order is over $89, free shipping.

SW mototires (no shipping charge if buying two)

Generally, BikeBandit has decent prices and decent cost for shipping. AMA members get 10% additional discount.

c.   Don't forget to do a thorough Internet search; and, do NOT forget about your local independent BMW servicer ....and even your BMW dealership.

17.   Nitrogen:  
There is BAD information, or just plain hype, on the use of nitrogen in any type of tire for road & off-road use.  
The facts are, that while there ARE benefits, use of nitrogen to fill tires is USUALLY NOT all that practical for anything but racing, as far as MOTORCYCLES are concerned.  

On the plus side, molecules of nitrogen are said to be larger than average air molecules.  These larger molecules do NOT pass through the rubber used in tires and tubes quite as easily as common air molecules.  Thus, pressure loss over time is lower, this is particularly so with higher percentage natural rubber tubes, as opposed to the lower percentage natural rubber, often just called plastic tubes.  On a practical basis, the slower loss is REALLY NOT a BIG difference.  One factor not discussed is the over-all 'thickness' of air, not just oxygen as often spoken about with regards to nitrogen use.  Average atmospheric air is 78% nitrogen, 21% oxygen, then comes water molecules, carbon dioxide (CO2), and rare gases.  Thus, the oxygen often talked about is actually only about a fourth of what the nitrogen is ...so the oxygen has even less effect than nerdy so-called scientific papers you may find on the internet, regarding tire pressure loss over time, ETC.   Another factor is that nitrogen is sold in pressurized metal containers, similar to welding containers, and the nitrogen can be relatively dry and pure ...or, rather not-so.  If using nitrogen to fill tires, from empty (just residual air), the highest percentage of dry nitrogen would obviously be best.  CostCo, which does NOT sell motorcycle tires, DOES use the premium nitrogen. 

A plus factor for nitrogen is that it is less prone to accumulate water vapor and is usually very DRY when installed into the tire, not so the 'outside air' from your average compressor setup, nor a gas station.   Water vapor in common compressed air can lead to rather wild fluctuations in pressure as the tire heats up & cools down.  Obviously, this is minimized by using clean, dry, air.   Nitrogen, due to its lack of extra affinity for water vapor, delivers a safer, more stable tire pressure, which can be somewhat important for very high speed driving (more so at racing speeds).  The final good point about nitrogen is that it does not contain oxygen, which tends to degrade rubber compounds over long periods of time.   The PROBLEMS with nitrogen are cost, not easily available, and if you top off the tire with too much compressed air, especially if the air is not dry, some advantages of the nitrogen is LOST.  This is LESS SO if the nitrogen that was used is a very high percentage type, and you add little air.    Nitrogen's good effects work with tubeless AND tubes.  If you are interested in a nerdy technical scientific answer to nitrogen versus oxygen in tires and tubes, go HERE:
http://www.getnitrogen.org/pdf/graham.pdf

When you have assimilated that, above, how about a more practical approach? ...easy to read, and basically correct, and fills in some things you did NOT get from the above link:  http://www.pedrosgarage.com/Site_5/Nitrogen_or_Air.html

NEITHER of those two articles covers what I have, in the above paragraphs.  NEITHER tells the full story, and I have.

18A.  There are instances wherein someone uses a tube-rated tire without a tube.   In some instances this is done with various motorcycle tires, but also done with two specialized sidecar type tires ....and, there are only TWO types of these square-profile sidecar tires available, as far as I know.   One in 18" and one in 19", and not from the same manufacturer.  The 19" is from Avon and is called the Triple Duty; the 18" is from Metzeler and is called the Block K.  I have tried nitrogen in these tires, and it appears that tire pressure loss IS SLOWER. Since the pressure loss from these particular two tires CAN be more rapid than with these tires when using tubes, this is something to consider.

18B.   Another usage is a tubeless tire used on tube-rated rims.  That brings up a whole story in itself & has its own article on this website: http://bmwmotorcycletech.info/section6.htm.   I have done preliminary testing;  leakage DOES seem less with nitrogen.   The bottom line is  that few of you are going to buy or lease nitrogen tanks for use at home ...but some bike dealerships may be using nitrogen.  I do not know if CostCo, or anyone else, has nitrogen available for motorcyclists ...maybe some BMW places do?

19.  TIRE WEAR:   The reasons for various "strange" tire wear & why one side of a front motorcycle tire wears so much faster than the other side ...& why downshifting for braking instead of using the brakes (downshifting for braking lowers tire mileage); & a LOT more, is in the following article, which is so good that I never wrote such a complete article myself:   http://www.rattlebars.com/tirewear/index.html. The only thing NOT well-explained, is why some two people with identical makes, models, & years of motorcycle, with the same make & model of motorcycle, same for the tires,  & identical pressure in their tires ....& the same riding habits, loading, &  styles, will, or can, have such different tire wear.   I'm not going to get into that, HERE, preferring to have some fun around the campfire some time.

20.  HYDROPLANING:
There are several types.  It does NOT have to be on water!  The TWO types of hydroplaning that YOU are likely to be concerned about are called (1) Dynamic Hydroplaning; and (2) Viscous Hydroplaning.   Both occur on wet roads, although the viscous type might be said to ALSO occur on ice.   I'll discuss Dynamic after I discuss rubber reversion, and lastly Viscous.

You are unlikely to be much concerned with other types of hydroplaning, one of which I will mention briefly:
Maybe you have a passing interest in the fact that if the brakes are used hard enough to STOP a wheel from rotating (and you are still moving), you MIGHT heat up the rubber at the contact point to where the rubber REVERTS to its PRE-cured condition;  then it just plain slides, like on ice. 

Dynamic Hydroplaning, occurs when the water in front of the tire can not be moved away from the contact surface fast enough.  The actual science deals with the water 'being rolled up'. That pressure is opposing the pressure the tire places on the wet surface (the weight of the motorcycle normally on that tire contact with the surface).   Various things have an effect on just when hydroplaning will occur: 
Softness & other factors of the rubber compound; road surface; tire profile; type of rubber; tread depth.  All those things would seem to be 'common sense'; and, yes, they are; but not to the degree you may think.  NASA did a LOT of testing; their testing has since been re-proven by motorcycle & car tire manufacturers, & the results are that a major variable in dynamic hydroplaning is from the PRESSURE in the tire.  Surprised?   The depth of the road surface water NEED NOT be very much at all.  If you are going too fast, you can and will risk hydroplaning ...and complete loss of control.

Hydroplaning CAN occur with quite deep tire treads ...at a speed, in miles per hour, as low as 9.9 times the square root of the pressure in PSI.   The factor for nautical miles per hour is 8.6, usually what is seen in various publications, usually not mentioning that it is nautical, NOR that this is "STATIC speed" ...and no explanation).  If you are MOVING, the speed is LOWER!    These points are almost never in any articles about hydroplaning!  NOR is it explained.

Welcome to Snowbum's anality, verboseness ....and propensity for providing extra (or too many) facts:

Once hydroplaning starts, it can REMAIN for MUCH lower speeds.   You are in danger of suddenly loosing control, from JUST hydroplaning on a wet road, even with really good & deep tire treads on good quality tires, at fairly low speeds.   If standing water is fairly thick, these speeds are much reduced, although some say there is no difference ...the REASON is that they are talking about CAR tires, or reciting from literature meaning CAR tires.   In any case, note that the speed at which hydroplaning occurs will rise ...a good thing ...as pressures RISE.  This is exactly backwards to what some, if not most riders believe.  They think that higher pressures mean less rubber on the road, more twitchy handling, etc.  They think that in rain, they should LOWER the pressures.  In one way, they are correct! ...the bike will feel less jittery, more planted, with lower pressures.  Since the front tire is usually the critical tire, & almost always has the lowest pressure, beware of excessive speed in the wet! ...you may lose control without using the brakes & much more likely to lose control if using the brakes, even gently.  Using the brakes USES UP traction.  Keep in mind that hydroplaning is just one factor; you can easily loose control due to insufficient tread depth, oil on the road or floating on the water, irregularities in the road, wind from the side; a host of other factors.    What all means is that you can loose control at a VERY much lower speed than that for JUST the published hydroplaning speeds.

"Viscous hydroplaning" is the type, at least on your motorcycle, that you might encounter if the road was rather smooth & the tire getting rather bald; that is, not a lot of tread is left.  This can occur at very low speeds and VERY low amounts of water on the road.  Less tread depth, more propensity to hydroplane.

If you are hydroplaning ...or beginning to hydroplane, it will be like riding on ice.   It is my opinion that on modern motorcycle tires if your tread depth is at least 3 or 4 mm, then the MAIN influence on the speed at which hydroplaning will occur, is the tire pressure and the thickness of the water on the road.   If you never ride in the rain, you won't likely worry about hydroplaning.  It is also true that there are very soft special rubber RAIN TIRES available for racing.   They have special treads, and a lot more, and are NOT part of my discussion, beyond this mention.

The safest thing to do if in the rain is to reduce your speed GENTLY AND GREATLY, and be gentle with leaning and brakes. It should go without mention that you should have good tread on your tires and normal tire pressures.

For common ordinary street tires for your motorcycle, some are better than others in the rain (or, just mildly wet roads).  The manufacturer's literature MAY ...or may not  ...be helpful in this regard.   I can say the same for anecdotal 'evidence' ...that is, can you believe what fellow riders say about a tire?   If a LOT of your fellow riders have run the SAME tire, and nearly the same pressures, and they live in really rainy areas ...well, I'd TEND to take THEIR word about the best street tires for rain ...over the manufacturer's claims, or from someone who rides gently once in a great while on damp roads.  With many tires, a visual look-see at the tread design will tell you a lot about how the tire displaces water.  You want a tread grooving design that moves the water out of the way of the tire rubber that is contacting the road.  Especially OUTWARDS.   Obviously, there is a limit to what such can do for you, particularly if the water is rather high/thick, or you are going too fast.

GENERALLY speaking, the LONGEST wearing street tires are the worst for rain.  BUT, this is not universally so.  Some premium long-lasting street tires are quite good when it is raining.

21.   Tire sizes; changing front fender brace for clearance, rear swingarm clearance, ETC:
Much of this information is also posted elsewhere's in this website.   It is shown here on purpose   ...and expanded upon.

The original FRONT tire size for all the early Airheads was 3.25 x 19 front.  For those wanting to go to metric sized rubber, the 90-90/19 fits the 19 inch front wheels, and the 100-90/19 will fit the early models for the front if the fender support brace is changed to the later wider type.    The later wider fender brace you would want is the 1977-1980 used on the /7 bikes.  The BMW part number is 46-61-1-234-907. 

The original REAR tire size for all the Airheads until well into the eighties was 4.00 x 18.  For those wanting to go to metric sized rubber,  the 110 or 120 size fits the wheels, and any problems will be with the tire sidewall to the swingarm area and possibly the tire sidewall to the discbrake stay (support).   The 110 size usually fits withOUT any spacer or brake stay changes.  Either the 110 or the 120 will do for the rear; but I recommend you NOT get the 120, unless you have specific reasons, such as the particular selected tire is rated for a heavier load; or, you also increased the front tire size to 100/90.  You MIGHT have to go to the slightly wider right side top hat spacer, which is 36-31-2-301-737.   SOME 4.00 rear tires may be too wide (especially Enduro types).   If your rear tire is touching either the swing arm or the disc brake stay at rest, or, especially likely is at high speeds, then you almost surely will have to use a wider spacer on the right side. The wider spacer here means the TOPHAT spacer located in the RIGHT side of the rear wheel of twin-shock absorber bikes & is easily removed & changed.   The wider spacer may not be needed on 1981 & later, but I HAVE seen it required.  There is a VERY MUCH wider spacer available too, see earlier in this article.  The stock spacer is 9.2 mm wide, the 36-31-2-301-737 is 10.7 mm wide.   On some bikes, with some tires, the tire will rub the swing arm at high speeds (~80+), & the spacer is a must ...unless you like the rubber smell, etc.  Usually most 110 tires fit without needing the spacer, say on an early eighties RS/RT.  On some rear disc brake bikes with the rear tire being a 120, I have had to ADDITIONALLY put a spacer on the left, a common very large diameter washer called a Fender Washer, available at most hardware stores.   Strangely (or not) that has mostly been when using an EARLIER snowflake wheel.  These snowflakes can LOOK the same, but are NOT.  That fender washer spacer moves brake stay slightly ...avoiding any possibility of tire rubbing at speed.  The swing arms vary a bit, BMW has made several changes in the width between the arms, the sidewall depression in the right side driveshaft tube, and more width changes in the 1980-1984 era, another reason for sometimes needing the spacer(s). 

When you change the right side tophat spacer to the longer (wider) one from BMW, that moves the wheel-spline-engagement very slightly to the left ...by about 1.5 mm.  There are naysayers that think the wear on the rear splines will be such that you cannot go back, and that is not really so, nor does the tiny shortening of the spline engagement have any large bad effect on spline life.   Changing the spacers does NOT affect bearing preload. 

The snowflake rear wheels on the RS and RT are slightly wider in rim width than the drum brake models.  The disc brake snowflakes are 2.75" rim width (measured at the official point for tire contacting the rim); and the drum brake snowflake rims are 2.5".  This slight 1/4" difference also makes the RS/RT disc braked bikes rear tires a bit wider...and puts a bit more rubber on the road too....and makes them a bit more suited to the 120 size tires.  Rim width is stamped into the metal of the wheels at the factory.

Don't forget that the under-seat and owner's booklet values (except perhaps the very last years) for tire pressure are TOO LOW for modern tires. Try about 33-34 psi front and 38-42 psi rear on ALL Airheads.

22.  Bridgestone tubes are of good quality. I've also had no problem with standard thickness tubes from Michelin.

23.  For TUBELESS TIRES being used on TUBE TYPE RIMS, the rim hole is 8 mm.  If you do not wish to enlarge the rim hole for a standard pull-in type of stem as used for tubeless tires, then there is a special valve stem that is available, even from BMW, that seals at the inside of the rim by means of an O-ring built into a recess of the stem unit.  The stem area of the rim, inside, must be machined flat for this to work well. It is best to do some machining on both sides for a small pull-in rubber stem.


This section was added to try to explain things often poorly understood ...if at all ...about such as tire profiles, sizes, differences in construction, warming-up effects, differences between road, track, and racing tires, etc.   A small amount of this information came from Harriet Ridley, a moto-writer in U.K., but I added a huge amount of information, deleted much, subtracted-from, edited, etc.  So, if you see some short familiar wording or even a part sentence, it might/could be attributed to Harriet:
 

Some of what you read below is very basic.  BEST TO READ IT ALL!

Tires work with your motorcycle to determine how hard you can brake, how fast you can accelerate and brake ...and how much you can lean ...and how well they keep you from loosing control.  The tires ALSO determine MUCH of the comfort and pleasure of riding the motorcycle.  The tires ARE part of the suspension.  The tires and how you use them includes inflation amount & how far you can travel before they wear out ....and, let's face it, tires aren't cheap for motorcycles.  There's almost never an 100% optimum tire to cover every situation. Each tire is a complex trade-off between grip, longevity and handling ...and tire manufacturer's budgets for R&D is pointed & poured into finding the most perfect compromise for a given situation. Three aspects are mostly responsible for a tire's characteristics:  compound, carcass, and profile; ...besides, of course, inflation pressure and road conditions including surface and temperatures;  so there's a lot for engineer's to work with.   In some situations, a tire manufacturer will consider the type of motorcycle, and likely suspension the motorcycle has.   The tread design is important, but not quite to the extent that the sales department of the tire company would have you believe.

If a tire were made from pure rubber it would wear EXTREMELY quickly and would never take the required vehicle weight.  Instead, the 'rubber' (often a synthetic equivalent) is mixed with carbon black to make it tough and resilient, then baked at high temperatures after being mixed with what could be dozens of chemicals and even silica/sand of specific fineness. Varying quantities and types of these things determine the compound's softness and its optimum operating temperature and its wear.    Many modern road tires have tire compounds that are longer lasting located in the center of the tread area ...that is, they have DUAL COMPOUNDS ...the compound away from the center of the tread is more grippy, or has other desirable characteristics.  This can make for a longer lasting tire, that handles well, in all normal conditions.

The tire grips the surface you are riding on by pushing itself against the surface so the softer the compound, the more it will grip. The softer compound will also be more abraded by the road, wear faster, as well as generate more heat by flexing more.

Regardless of compound, there's a temperature at which tires operate best for the purpose they were specifically designed for. Unless a tire reaches its optimum temperature AT THE CONTACT POINT ...the compound won't soften enough to provide the intended grip - hence the use of silica in road compounds to ensure a certain level of grip in cold and/or damp conditions, & why it is important to warm up your tires carefully before high performance riding.  Silica can INcrease tire tread life.   There is a temperature at which all tires will overheat; & many have found that point with heavy loads, high speeds, etc.  After basic construction a tire is "cured" in an oven at a certain temperature, no higher, no lower, so that everything sticks together and, especially, the "rubber" obtains its basic desired characteristics.  If you are riding your motorcycle and that tire goes over that same temperature for too long, it will de-cure.  At first it squirms and loses traction as it breaks down chemically, then it delaminates as it breaks down physically. So each tire is carefully tailored to suit its intended purpose.

For any given tire construction, including compound type, the DEPTH of the TREAD has a very considerable effect on performance, hardly just on tread life.  Common sense tells you that a deeper tread will last longer (partially true, but not always true), and will work better for you in rain, etc. (mostly true).  BUT, a deeper tread also squirms or distorts more during riding, and thus produces more heat, which wears the tread faster.  Obviously there are limits, and obviously there is an optimum tread depth (and design).

TRACK-ORIENTATED: This compound is designed for plenty of grip at constant, high temperatures reached by the extreme pace maintained on a track:  hard acceleration, hard braking and high cornering speeds. Because it is designed to live at high temperatures the race compound will also take longer to reach its peak. That is why tire warmers are used in the pits. If you use these tires on the road and even if you ride quite hard, you'll be forced to slow down for traffic and stops, etc., and every time you do so the tires will cool off and take a long time afterwards to even approach their required temperature again. Keep this up and the tires will wear fast and shed rubber through cold tearing; so they may look like they're being used hard, but in fact they are disintegrating from misuse.

HEAT CYCLES:  Each time a tire goes from hot to cold it IS SOMEWHAT RE-CURING ITSELF AND IT BECOMES HARDER, as chemical oils used in the tread to maintain compound are released (hence, in some cases, the bluish color you sometimes see on a tire's tread after hard use). While this is minimal on a road tire, it becomes more extreme on race compounds. Specialized race tires are designed to go through only one heat cycle before compound deteriorates.  Track-focused tires are a lot more sensitive to heat cycles than their road equivalent. Hence tire warmers not only bring tires up to their required temperature, they also maintain a constant temperature between races or sessions to minimize heat cycles.  ROAD tires are designed for all the heat cycles you might need.

CARCASS:  The carcass gives the tire its required strength; it's more resilient on a road tire & how much the carcass lets the compound flex affects heat generation and its rounded shape. But because the tire's contact patch is flat the tire has to compress & distort where it meets the ground. This shape-changing means some of the rubber has to slide across the road to achieve the new shape, causing wear, while the constant flexing of compound & carcass at this point generates heat.

The old-style cross-ply tires used many layers of plies molded at an angle to give the tire strength. But the amount of material used made them heavy and THAT generated a lot of heat, so harder compounds had to be used to maintain the right temperature.  Another compromise had to be made with tread depth, because increasing tread depth increases heat generated.

As bikes became faster, and some became lighter and some more agile, tires had to improve. Bias-belted tires appeared as a step on the path to radial heaven, and bias belted tires are still in use on big heavy bikes where sidewall stiffness is more important. But radials broke new ground thanks to clever layering of fabric. A radial tire is not only lighter and more responsive, it also runs cooler as the tire distorts more easily, a special type of distortion and angle that seems to be opposite the flexing increasing heat that I have previously described (and moreso with running tubes).  Running cooler means you can use a softer tread for better grip with no increase in wear.

PROFILE:   AN EXAMPLE.  On a 100/90-19 FRONT tire, 19 is the diameter of the wheel rim in inches, measured at a particular point of the sidewall area of the wheel; 100 is the width of the tire in millimeters, and 90 is the percentage height of the sidewall compared to the tire width.  The higher the sidewall, the more slower steering but good stability. Lowering the sidewall by 10mm the tire acquires a steeper profile - it is more 'triangulated'. The results are quicker steering and more grip when leaned over, but anywhere in-between straight line and transition from upright to lean angle is less stable.  This explains why the multi-cylinder crotch-rockets have such wide rear tires. The carcass's crown radius also shapes the profile.  The shape of the carcass's crown radius also dictates the way a tire handles, which together with the sidewall determines profile.

The sidewall also acts as suspension for the tire (and motorcycle itself!) and comes in varying degrees of stiffness: a big heavy touring tire needs the thick bead filler found in the sidewall of touring tires for added strength and stability. If reducing the height of the sidewall, the tire is less capable of absorbing surface irregularities and tends to hop when cranked over, causing the bike to understeer. 

REAR tire size also affects performance: a narrower section tire will steer quicker, while a wider section tire will last longer by coping better with power battering.   A result of this is that as engine horsepower and torque is increased, the rear tire works best by being wider.  In some instances, even with same or even a bit less horsepower and torque, the rear tire size section is increased, especially if the motorcycle is intended to be used more aggressively in a variety of conditions. 

These various explanations can point out why the R80ST and later GS had a 120 rear tire ...yet the R80G/S had a skinny (and larger diameter) front tire.

A road tire will greatly outperform a race tire in terms of acceleration, cornering speed, braking, durability and stability ...over the course of a road trip. You will have to do some thinking to understand that.  You may need to re-read quite a few paragraphs.

RADIAL TIRES:  A tire's compound (tread) is molded onto (and somewhat INTO) the carcass. On a radial tire the carcass is typically made of two plies with strands usually of steel, aramid (that's Kevlar), or some other material. The first ply is usually a radial ply that runs at 90 to the tire's rotation (folded under the steel bead), while the second usually runs in the direction of the tire's rotation to minimize expansion at speed.  The top two plies are cross-plies (with usually Nylon strands) placed at an angle to add strength.  Some new tires now becoming available for Classic Bikes (to improve handling) have different ply angles (even zero). The bead that you'll find on all types of tires holds the tire to the wheel rim with a 'rubber' bead filler to strengthen the sidewall.   I need to get some photos of these things to put here, as they are hard to visualize properly.



TIRE FACTS:

• Low pressures cause tires to move around and generate too much heat, while high pressures will reduce the contact patch and the tire will struggle to warm up.   Check your pressures when cool to baby bottle temperature.  Many tire manufacturers, due to lawyers and threat of lawsuits, will simply repeat the motorcycle manufacturer's recommended tire pressures.  Those pressures can be VERY wrong for YOUR tires and riding.   Typically and generally, the real tire pressures you should use for street riding on OLD BIKES with modern tires will be HIGHER than the motorcycle manufacturer said for your bike when it was built.  Early Airheads used old soft and ribbed tires with rubber compounds designed for lower pressures, such as the Continental RB2/K112.  For modern tires, such old pressures under 30 or slightly over 30, will be QUITE WRONG for handling and tire life.  You will probably find that your bike, when equipped with modern tires, is best, OVERALL, with 33-36 psi front, 38-42 psi rear, depending on speed, aggressiveness, and loading.

• New tires need careful scrubbing in to get rid of the slippery mold release agent used at the end of the production process.   Some say up to 200 miles. MY experience is that 50 miles is good enough if you scrub the tire after it is mounted and inflated, with soap and water, then flush the soap off. Just be particularly careful during initial 20 miles, and be sure your break-in miles include some steeper turns ...head into them gently until the tires are scrubbed in.  Breaking in a tire is not just scrubbing & abrasion, but the tire compound itself is breaking in, and this is hardly ever mentioned; ....so, until you have accumulated a hundred or so miles, avoid any quite aggressive riding style. Failure to properly break-in tires WILL result in distinctly poorer performance ...and tire life too!

• A slick's uninterrupted compound (or tread) optimizes dry grip, but it is unable to clear standing water and some types of debris. Hence a pattern is molded into a road tire's tread. A tread pattern also generates heat by flexing ('block movement') and is usually no more than 8 mm deep to prevent weave and excessive heat build-up.  Mind what I have said about depth and tire rating (V, H, S ...) much earlier in this article, ...........and about tire mileage.

Race tires are available in different compounds and mix-matching can provide an ideal compromise between grip and longevity. A softer tread is used on the front for better grip while the rear gets a harder compound to cope with the power battering. The front is also sometimes fitted with a flatter, more stable profile while the rear can be more triangular for quick steering. Manufacturers do all the work for you on road tires so don't mix-match on them, unless you know what you are doing.

• Specialized race tires get different compounds on either side of the same tire, so where a track has a predominance of right-hand corners the compound will be harder on the right but softer on the left. Similarly, Bridgestone's dual-compound road tires get softer edges for good corner grip with a harder middle to reduce tires squaring off with the accumulating non-cornering miles.

• Tire wear is a complicated subject.  Everyone knows that over-inflation causes twitchy handling & faster center of tread wear; and, under-inflation causes sloppy handling and the wear pattern moves closer to the edge.    Common knowledge is that tire GRIP, LONGEVITY, and ROLLING RESISTANCE cannot all three be optimized at the same time.   THERE IS SOME TRUTH in this.  It is also true that tread patterns have a lot to do with clearing of water, mud, etc., and grippy-ness. 



Scalloping:  Some have questioned why tires sometimes show scalloping of the tread.  This is almost always seen, to any extent, only on the front tire.  Very few seem to know WHY this really happens, and they blame it on a faulty tire or faulty tire design.    Some tires are more susceptible to scalloping than others.  A famous instance is the Metzeler ME33 front tire.  This was nearly the first V tread pattern that performed really well for paved road bikes, but some had scalloping problems....which seemed not to affect, much, actual handling, but LOOKED bad. 
These tires tended to scallop from weak springs, poor shocks, sometimes excessive loads for the pressure used.   There was nothing basically wrong with the tires.   But, because the tires could, and often did scallop, they got a poor reputation.  Funnily, the V-tread design got copied by some other makers, particularly Chinese makers.   That the tires were particularly good on wet paved roads, and delivered a very prominent notification before slipping-out, seemed to escape the criticisms.


Rev:
01/28/2004:  Initial 'dated' upload after final revisions.
02/03/2004:  Expand information on handling and tire size uses slightly.
02/09/2004:  Add #14.
09/01/2004:  Update article, with better clarifications and stem part number, etc.
04/03/2005:  Changes in emphasis throughout, and add some hyperlinks and add #15
04/20/2005:  Add tire make and model description information in more depth.
05/13/2005:  Minor updates, primarily on the top hat spacers.
08/07/2005:  Add comments on karoo and scorpion and info on Discount m/c tire and acc.
08/13/2005:  Update section 4.
09/24/2006:  Add 17.
08/19/2009:  Updated.
12/15/2009:  Revise & add more tire model information.
05/12/2010:  Revise for clarity, combine some areas, add more information to what is now 23.
05/31/2010:  Add 24.
12/22/2010:  #25 finally added/updated.
12/23/2010:  Updated tire recommendations.
03/14/2011:  Add #26
06/20/2011:  Updated recommendations for dual-sport tires.
06/28/2011:  More information on tire flexing, contact temperature, use with tubes.
08/04/2011:  Correct math on hydroplaning, add a bit more to that info too; combine into one place.
04/25/2012:  Update tire information slightly, clarify minor things.
06/17/2012:  Add Bridgestone tubes; update vendors.
07/11/2012:  Minor updates on Roadrider tires and add #28.
10/14/2012:  Add QR code, add language button, update Google Ad-Sense code, minor other things such as updating URL in #24.  Language button removed later, as had scripting problems with it.
01/22/2013:  Updated article to give more information, in depth, on tire types and uses, its own section.
04/23-24/2013:  Minor updating, tire pressure reference, etc.  Edit to reduce SOME duplication & improve clarity at various places.
09/20/2013:  Add Conti-Attack listing & info.
10/07/2013:  Add tire photos, and a few scattered comments.
04/08/2014:  Update the entire article.  Fix typos, add information, fix numbering system, etc.
04/23/2014:  Update various places.  A bit more 09/25/2014
11/02/2014:  Add link to #5
05/24/2015:  Add note to Avon RoadRider's. Additional note regarding steel plies pros/cons, on 05/25/2015 & 06/12/2015.  Testing notes on 06/19/2015 & 06/26/2015. 
10/02/2015:  Updated for extensive testing on Roadrider's.
11/04/2015:  Updated for clarity.
11/14/2015:  Heindenau review.   Clean up article some, with fresh formatting, more concise statements, on 11/20/2015, & additional notes in late November. Incorporated my notes (I'd misplaced them) for my Michelin tests....found them stuffed into one of my 10,000-pockets-riding-jacket.
12/11/2015:  Increase font size to 14pt, finalize changes to meta-codes, clean up due to font changes.
01/21/2016:  Some updating, due to changes in comparo methods; to bring article more in line with the improved performance of the latest tires.
03/27/2016:  100% re-do the article:  Update metacodes, primarily for use on small devices.  Standardize & reduce use of fonts and colors.  Justify left.  Convert tire symbol list to a narrow table format.  Eliminate numerous redundancies.  Clarify some details. Add some links, including two to give the full story about nitrogen use. Miscl updates in June and July....mostly tire comments previously not included.
08/09/2016:  Updated for RoadRider cracking, cautious, not-recommended, etc.  More on 09/04/2016.
11/01/2016:  Major revision.  Updated metas, scripts, H.L., layout, fonts, and MANY HTML simplifications.  Expand upon nitrogen use.  Expanded explanations regarding all details of tire construction, size, profiles, etc.  
11/13/2016:  Latest RoadRiders tests (stability).
12/01/2016:  Some shortening of article (remove several paragraphs of personal stuff).


copyright, 2014, R. Fleischer

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Last check/edit: Thursday, December 01, 2016