Thoughts on tyre uneven wear

[Ajlelectronics]

Coming back from Portsmouth tonight, I was musing things as you do...

Aviators will understand about "sideslipping" where the aircraft is flying in a straight line, but is out of balance. Thinking about this, led me to experiment....

What I have noticed on the bike is that it is possible to sit one side or the other in the saddle and counteract it with a small amount of lean. I wonder whether this might be a possibility for the cause of tyres wearing one side more than the other? I have never seen this problem though.

Do some riders sit slightly off centre?

[RonKMiller]

MC tires wear on the left side more in the US - since you spend more time in the arc of left hand turns vs. right. Opposite for you folks that drive on the "wrong" side of the road.

I never had any trouble driving round-a-bouts in England, but shifting a car with my left hand was quite a challenge! ;)

[bruce2000ltc]

Coming back from Portsmouth tonight, I was musing things as you do...

Aviators will understand about "sideslipping" where the aircraft is flying in a straight line, but is out of balance.
I've been thinking about the same thing...but from a different perspective.

I always noticed on my '00LT and my '05LT that when I took my hands off the handlebars on the highway that they didn't track perfectly straight. The bike always needed to be corrected. Both bikes were "sideslipping" or "crabbing" down the highway and required a very slight correction on one side of the handlebar to keep them going straight. It is my thought that this slight deflection of the front wheel is what contributes to the uneven wear on the front tire. This deflection would cause one side of the front tire to constantly be scrubbed and over time this wear would have to show up.

With 90,000+ miles on these two LT's I've changed a lot of tires and when installing the front wheel I always left out a step; taking the bike off the centerstand and compressing the front forks with the axle clamp bolts and the axle bolt finger tight. The purpose of which is to get the front end aligned before you tighten the bolts. I skipped this step because it's a PITA and I'll bet lots of others, even dealers, do the same. Well the last time I changed tires I didn't skip the fork compression step and now my bike tracks perfectly down the road. 7,000 miles later and the front tire is wearing evenly - but it's a Metz 880 and they seem to be less susceptible to uneven wear so I won't know for a few thousand more miles.
I don't think this is the end-all answer to the uneven tire wear question but I do think it is a contributing factor.

Ron: I like the longer arc theory but I've got 400,000 or so miles on a lot of other bikes that didn't exhibit the odd wear on the left side of the tire that my LTs have. There has to be something else at play.

Bruce Hodges

[cfell]

yup..

I've practiced focusing on balance on my bike where it's the least pressure, MINIMAL touch on bars.

Interestingly, seems the front tire is wearing much better...

[Woolly]

Going back to your aviation reference, crosswinds will also make the bike out of balance.

[RonKMiller]

All I can say as that having been a Commercial Pilot for the last 25 years (and riding mc's for 43) I can ASSURE you guys that you are not going down the road sideways! ;)

Read this link completely from beginning to end - I cannot find one thing in his analysis that I can fault.. :think:

http://www.rattlebars.com/valkfaq/tirewear/

[RonKMiller]

I always noticed on my '00LT and my '05LT that when I took my hands off the handlebars on the highway that they didn't track perfectly straight.

Due to road crown. Both of my 01' LT's did this - a little over 100K on the first and just over 25K on the second.

...taking the bike off the centerstand and compressing the front forks with the axle clamp bolts and the axle bolt finger tight. The purpose of which is to get the front end aligned before you tighten the bolts. I skipped this step because it's a PITA and I'll bet lots of others, even dealers, do the same.

Absolutely the correct way to do it, and all it takes is an extra minute! I've never seen anyone actually torque the pinch bolts either... Most standard torque wrenches don't read down to - what is it - 10nm? BTW, I've got a calibrated "micro" torque wrench that anyone can borrow for a $300 deposit and shipping - it just sits in my took box rather lonely, only seeing daylight every couple of years...:o

The only real alignment that can be done is to make sure the front and rear wheels are pointing in exactly the same direction - with the rear of the LT "locked" in place this becomes impossible. When I raced short track alignment was hyper critical. We used two strings pulled taught with heavy weights and ran them parrallel to each other along the rear sidewalls so that they just touched the outer diameter of the tires. Measuring carefully to keep the same distance in the front we would wiggle and slowly tighten the rear axle so that both wheels were lined up and touching the strings at eight points. While kind of archaic and not real scientific it did indeed work.

Ron: I like the longer arc theory but I've got 400,000 or so miles on a lot of other bikes that didn't exhibit the odd wear on the left side of the tire that my LTs have. There has to be something else at play.

The extra weight of the LT, not to mention that braking technique plays a lot into excess tire wear. Even slight braking before curves will dramatically increase wear. You and I both know that braking before a curve is the only way to go - yet I often find myself going in too "hot" :eek: in corners with this 800 lb. beast and end up clamping them on a little too late. ;)

Really bad for tires and my adult diaper budget. :D

[messenger13]

Do some riders sit slightly off centre?Indeed! I have witnessed this on many occasions and have corrected the riders.

Also, roads are graded toward the berm for drainage. This also causes motorcycle tires to wear unevenly.

[RonKMiller]

Indeed! I have witnessed this on many occasions and have corrected the riders.

Also, roads are graded toward the berm for drainage. This also causes motorcycle tires to wear unevenly.

Thank you Joe for "correcting" these lopsided riders - maybe one of their butt cheeks was hurting? :histerica

Oh yeah, time to explode another urban myth about road crown causing uneven tire wear on motorcycles - the geometry just does not compute. I didn't write this but I agree with the author's explanation 110%:

"But what about road crown? Plausible and many claim it, but road crown plays no part whatsoever in left side tire wear. Though it does seem logical and also allows that in European left side driving countries, the crown is opposite which could explain right side wear there - road crown just doesn't hold up under scrutiny. The main reason the theory falls on its face - road crowns are simply not steep enough. If you examine a picture of the front tire upright (http://www.rattlebars.com/valkfaq/tirewear/wear01.html), you can see that even a very steep road crown (one inch drop in one foot run) would not even contact the tire at the necessary angle to produce the evident wear. Typical road crowns are much much less (three inches drop per twelve foot run). In fact, if one examines the picture of the tire (http://www.rattlebars.com/valkfaq/tirewear/wear03.html) one can see that where a road crown would actually contact the tire, there is a PEAK rather than a valley (check our extreme wear pic at the top of this page). Plus, as described in the paragraphs above, road crown contact is mostly "rolling" contact which produces very little wear if any at all. Just so there is no misunderstanding, road crown plays no part whatsoever in left side tire wear. Road crowns, if they exist at all on a road, are completely inconsistent and vary greatly as to pitch, vary even more greatly in turns (road engineers do indeed "bank" turns), and crowns in no way contact the tire at 20° off horizontal (http://www.rattlebars.com/valkfaq/tirewear/wear03.html) where the wear occurs. Road crown does not cause side tire wear."

[messenger13]

Thank you Joe for "correcting" these lopsided riders - maybe one of their butt cheeks was hurting? :histerica

Oh yeah, time to explode another urban myth about road crown causing uneven tire wear on motorcycles - the geometry just does not compute. I didn't write this but I agree with the author's explanation 110%:

"But what about road crown? Plausible and many claim it, but road crown plays no part whatsoever in left side tire wear. Though it does seem logical and also allows that in European left side driving countries, the crown is opposite which could explain right side wear there - road crown just doesn't hold up under scrutiny. The main reason the theory falls on its face - road crowns are simply not steep enough. If you examine a picture of the front tire upright (http://www.rattlebars.com/valkfaq/tirewear/wear01.html), you can see that even a very steep road crown (one inch drop in one foot run) would not even contact the tire at the necessary angle to produce the evident wear. Typical road crowns are much much less (three inches drop per twelve foot run). In fact, if one examines the picture of the tire (http://www.rattlebars.com/valkfaq/tirewear/wear03.html) one can see that where a road crown would actually contact the tire, there is a PEAK rather than a valley (check our extreme wear pic at the top of this page). Plus, as described in the paragraphs above, road crown contact is mostly "rolling" contact which produces very little wear if any at all. Just so there is no misunderstanding, road crown plays no part whatsoever in left side tire wear. Road crowns, if they exist at all on a road, are completely inconsistent and vary greatly as to pitch, vary even more greatly in turns (road engineers do indeed "bank" turns), and crowns in no way contact the tire at 20° off horizontal (http://www.rattlebars.com/valkfaq/tirewear/wear03.html) where the wear occurs. Road crown does not cause side tire wear."Ron Miller: He can compress the most words into the smallest idea of any man I know. :rotf: CLICK HERE (http://www.bmwlt.com/forums/showthread.php?t=26883) for reference.

[RonKMiller]

Ron Miller: He can compress the most words into the smallest idea of any man I know. :rotf: CLICK HERE (http://www.bmwlt.com/forums/showthread.php?t=26883) for reference.

EXCELLENT! :D