Any ideas on why tires cup as they wear?
1990 K75 RT
Any ideas on why tires cup as they wear?
1990 K75 RT
Generally speaking we are riding more in a straight line than in a curve, but it also deals with rubber compound. That is why tire manufactures make the tires in a different compounds in the center and on the sides (harder in the center, softer on the sides). The only tire that did not cup was a z-rated tire, were the compound was so soft that it was done in about 5K. I loved te z-rated tire, because it was a very soft compound had incredible grip, but because it was so soft also wore out so fast. My budget can not afford that, otherwise I would mount them in a second flat....
My 2 cents anyway.....
Keep the rubber side down!!
1986 R 80 RS
1992 R 100 R
BMW MOA Life member; Ironbutt Member; Airhead Member
My personal experience with cupping tires is insufficient tire pressure. I experienced cupping tires on one of my long distance tours a few years ago while starting off with new Metzelers and running the manufacturer's recommended pressure of 32psi. After inflating the tires to 36psi front and 38psi rear, the cupping ceased and I've no longer had cupping occur on any of my tires regardless of make. Also resulted in better performance, longer mileage, and better feedback.
Mike V. / San Diego
78 R100/7 [orig. owner] / 81 R65 [restored]
ABC-MOA-AMA / http://tinyurl.com/4df7hgs
Interesting. Under inflated, over inflated, bumps in the road, crowns, dead possums sticking to your rubber and throwing everything out of whack. Hmmmmmmmmmmm. I aways thought they just wanted to sell me more tires. Dang.
I've found that they also can cup if they are not inflated enough, and/or, if the tire is actually too wide for the rim that it is mounted on. IF the tire beads are too close together, the tire's profile is squeezed in, making the center of the tire tread contact patch more sharply curved with a narrow contact patch. Subsequently riding and cornering on that tire will tend to cup the edges and leave you with a narrow ridge contact patch inthe center of the tire (this is most likely on front tires, BTW).
I experienced this on my 1998 Kawasaki Concours, which, while it came from the factory with an OEM model 120/80-17 tire, the dimensions of that tire are actually much smaller than any other 120/80 tire you can buy. Researching the minimum rim width application info for various tires, I learned that the OEM tire was the ONLY 120/80 front tire which supported application on a rim as narrow as the Kawasaki had. All other brands of tires which I had tried over the years actually were not meant to be fit onto such a narrow rim, and their profile was altered and they would cup. Increasing air pressure would less the problem somewhat, but they would still cup, some worse than others, even though I was buying the "right" metric size tire.
Of course, not all xyz/ab series tires from different manufacturers - or model lines within the same mfgr - are actually those exact dimensions. Some are wider than others. But, all will work out to be the same RATIO of height to width proportionally.
My last set of tires on the Kawi, I researched and bought a smaller front tire - a 110/80 which actually showed in the mfgr charts to support the rim width of my bike. It has only been ~2K miles so far, but absolutely NO SIGNS OF CUPPING YET!! I think that I am on to something.
hope this info is of some help to you.
BMWs in my garage: 1982 R65LS, 1978 R100/7
Ambassador BMW MOA Ontario Canada
President Niagara BMW Riders #298
Knights of the Roundel #333
1977 R100RS with 516,000 miles
I had an R1150RT and the new front Metzler started to cup. I showed it to a Metzler rep at a rally. He asked me if I was running the BMW recommended tire pressures - I said yes, I checked them before every morning of a ride. He said to bump them up four pounds and the cupping would stop. It did.
05 K12S . 86 R65
Paul Glaves - "Big Bend", Texas U.S.A
"The greatest challenge to any thinker is stating the problem in a way that will allow a solution." - Bertrand Russell
I have Bridgestone Battlewing 501front and 502 rear. Im a heavy guy at 250# so i set the ESA on my bike at "normal" and for 2 up with gear. I figured this would compensate for "heavy me" and the stuff I tote to and from work. The bike is an '08 GSA. I currently run the air pressure that BMW prescribes for 2 up/gear at 36# front and 42# rear. I find that I get slightly bumpy in the center tread on the front and some fairly significant (in my book) high and low areas between tread sections on the rear. I believe this to be called cupping. I read here.... over pressure, under pressure etc....
What is the proper approach to eliminate this behaviour ? Am i riding with too much inflation or not enough ?
Hopefully someone with real knowledge/experience or someone from one of the tire companies can respond with corrective action Pleeeeease?
With regard to autos, a worn out suspension can cause cupping. I don't see why that would not also be the case with motorcycles. Granted, I'm just guessing and could be wrong.
I heard from the place I get my tires that the tires made today require higher pressure than when our bikes were made. Consequently, I run the double up pressure for solo, and I haven't had any troubles. Could just be lucky though.
Jeff in W.C.
1988 R100 RT (the other woman)
"I got my motorcycle jacket but I'm walking all the time." Joe Strummer
the max pressure under load for those Bridgestones is 42#.... I run 42 in the rear and 36 up front and get the cupping as a result. Does cupping come from over inflation or under inflation??