In Reply to: Absolute Horse Sh*t... posted by Sean on January 06, 2000 at 15:47:30:
I have had the dreaded tire cuppping problem for some time. I have gone to various reputable tire dealers/installers in my area. They have given various reasons and solutions for this problem, these are as follows:
Background- 99 M3 with Michelin Pilot Sports, first noticed problem at approximately 5K miles, currently at 18.5K miles.
1) Various Tire installers- Alignment problem- 2 alignments in one year- it has not resolved the problem.
2) BMW Dealer-All M3s do this because of their "sport" suspension.
3) Michelin Tech Support- All Michelin Pilot Sports will do this because of the aggressive suspension on the cars to which these tires are fitted. Also, the staggered sizes on the M3, and the directional tread of the Pilot Sport, does not allow for correct tire rotation, in turn exacerbating the problem.
4) Very Reputable Tire Dealer/Installer- Rotation problem (see above)
5)Personal Experience- Cupping can be reduced by increasing tire pressure. Cupping was increased when I ran the door jamb indicated pressure levels . Increasing the level has reduced the problem, some people recommend running 38 lbs up front to eliminate the problem. I still run 35 up front and back. Someday I'll get same size wheels and tires and rotate them religiously.