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Posting this for a friend who replaced the rear tire of a 2009 Cayman S with 500 miles and 3 Autocross events on the tire. The autocrosses were 5 runs per event and 60 secs/run. He asked me what would cause cording at the very edge of the tire over only 1/3 of the tire with normal wear over the rest of the tire and also the other 3 tires. I couldn’t. The car is lowered and has -2.0 degrees rear camber so we looked for rubbing but couldn’t find any. He runs 32lb pressure hot on all tires at Autocross and normal cold pressures on the road. He replaced the two rear tires but is worried this will happen again. The tires are Cup2. Any ideas what would cause this?
That is the outside of the same tire at the same time? Assuming that, that is a *lot* of wear variation. An educated guess could be balancing, but even on the rear I would think that would be felt. Likewise, a suspension defect would be felt as well. Maybe a bent wheel.
I'm having a hard time imagining a tire defect doing that.
That is the outside of the same tire at the same time? Assuming that, that is a *lot* of wear variation. An educated guess could be balancing, but even on the rear I would think that would be felt. Likewise, a suspension defect would be felt as well. Maybe a bent wheel.
I'm having a hard time imagining a tire defect doing that.
-Mike
My thinking is that anything in the suspension/wheel that would cause that uneven and severe wear in 500 miles, would be felt.
The pics were the same time, same tire. It is winter here in Florida but temps were never below 65F. Getting the tire from the installer tomorrow and will try to get some more pics.
My $0.02: Most likely a tire defect. Alternate hypothesis: A teenager in the house practicing handbrake turns late at night. Very unusual wear pattern!
Defect. They will probably warranty it. I had a similar thing happen to P Zero's with very little miles on them and Pirelli replaced them for free through the local P dealer.
Thanks guys he is going back to the dealer today to talk to them and pick up the old tires. I should mention these tires were new when he installed the springs and had the car aligned all done at the Porsche dealership. I run Cup2 on the GT3 with the same pressures and camber. I run the same events and get 5000 miles plus I do 4-5 track weekends at Sebring and have never seen that kind of wear. Mine usually heat cycle out before they run out of tread.
I'm confused. You're saying the 2 photos are of the same tire? Doesn't look like it to me. Those are 2 different wheels. That said, the overall wear pattern in the first photo looks similar to Cup 2s I've used. Have seen that type cording after 20-25 cycles on GT3 and GT4 running only moderate camber (approx. neg 2 deg).
Those are the pics he sent me. Got to take pics of the tire off the wheel today. The wear looks more consistent around the tire to me. I am guessing those were the two rear tires, each side. I mistook them for the same tire. Apologies for the confusion.
Put the car car on an alignment machine today and no loose suspension components, or bent rims. Only toe was off but not a lot.
04-19-2018, 07:32 PM
Unusual tread wear
