Dave P Posted September 15, 2014 Share Posted September 15, 2014 Hey all- R1100RT, I need to buy a rear tire for my RT. My rear still seems to have some tread in the center, but is quite "scalloped" on either side. Rear currently is a Michelin Pilot Road. I've got a Bridgestone on the front, BattleAxe if I remember correctly, Only about 3000 miles on it, looks like it is starting to scallop as well. Is this scalloping, or cupping due to the tire, the bike or the rider? Or is that just what they do? It has always seemed odd to me that a bike tire would wear like this. Thanks! Dave Link to comment
mneblett Posted September 15, 2014 Share Posted September 15, 2014 Not unusual. Braking, cornering, acceleration forces can accelerate tread block edge wear. The harder the riding, the greater the tendency to wear the edges. Proper inflation minimizes, but cannot eliminate, "cupping." Link to comment
dirtrider Posted September 15, 2014 Share Posted September 15, 2014 Evening Dave Some is: tire construction, some in how the tire is used, some motorcycle geometry, some is rider, some is road surface. Basically a motorcycle tire has a round profile so when riding straight down the road the tire is traveling on the (center) largest diameter. As the bike leans over the tire is leaned onto a smaller diameter so the tire has to instantly speed up to maintain same road speed. Then when the bike stands straight up again the tire must quickly slow back down as it goes back to the larger diameter center. The continual speeding up & slowing down scrubs the tire & causes cupping or feathering. Some tires are more prone to cupping or feathering due to softer rubber, tire construction, or tread design. On the front tire, heavy braking also tends to wear the leading edges of the tread & if low on air pressure tends to distort the tread during braking causing more uneven wear. Link to comment
Dave P Posted September 16, 2014 Author Share Posted September 16, 2014 Thanks for the notes, I did a little research after I made that post and it sounds like bike tires just wear like that. I must admit that I haven't been diligent about watching my tire pressure, so that has probably sped up the cupping a bit. I'll keep a better watch on my tire pressure from now on. D Link to comment
tobyzusa Posted September 16, 2014 Share Posted September 16, 2014 If you run tires with pressure that is too low they will scallop. What pressure are you using? Link to comment
Dave P Posted September 16, 2014 Author Share Posted September 16, 2014 Well it's just me riding, I've been doing 31 front 36 rear, but I noticed a few weeks ago that the rear was down. Sounds like even with perfect pressure all the time they will scallop, maybe just a bit slower than with air pressure too low. Link to comment
mwood7800 Posted September 16, 2014 Share Posted September 16, 2014 31 damn, I try to stay at 40 42 Link to comment
Dave P Posted September 16, 2014 Author Share Posted September 16, 2014 damn, my 1100RT owners manual says one up 31 front, 36 rear. Am I missing something here? D Link to comment
mneblett Posted September 17, 2014 Share Posted September 17, 2014 The age of your manual. Tire design has advanced in the ~15 years since the R11RT was released. Modern sport/touring tires work at higher pressure. Link to comment
CoarsegoldKid Posted September 17, 2014 Share Posted September 17, 2014 Yes, in my experience low tire pressure is the major cause of what I call deformation of the tire blocks. On a smooth surface like a driveway I have even felt the vibration. I can hear a change in the tire noise between straight up and leaned over when the the deformation is pronounced. Experiment Link to comment
Dave P Posted September 17, 2014 Author Share Posted September 17, 2014 OK, well I guess I am missing something here- I was going by what my manual said. Seems I need to kick it up a notch. 42 front, what about rears? 46,47? Dave Link to comment
CoarsegoldKid Posted September 17, 2014 Share Posted September 17, 2014 I run 37-39 front, 40-42 rear. This works for me with my gauge, my selection of PR3 tires, load weight changes and manner of riding over the last 106K miles. I just changed to PR4 tires, which I found to have softer sidewalls, so the calculus may change but it's a starting point. It may take a few thousand miles to dial it in. Few if anyone has a calibrated air gauge and even so does it correlate with yours? Link to comment
UberXY Posted September 17, 2014 Share Posted September 17, 2014 My guess is your tire pressure is too low. I had some scalloping on Michelins on an R1150RT, and I talked to a factory rep about it. He asked if I was running BMW spec pressures, and when I said yes he said that's the problem. I bumped them up four pounds and the scalloping stopped. What someone said earlier about the manual specs having been written for 15 year old obsolescent tire technology hits the nail right on the head. Link to comment
Bologna Posted September 18, 2014 Share Posted September 18, 2014 39F 40R My PR3's wear great ! Link to comment
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