I had been experiencing a shimmy in the steering wheel lately when I would be driving 65mph+. Checked the tire pressure and all was ok. Had the wheels removed and checked on a balancing machine and they were pretty well balanced. I did notice, however, that the insides of both front tires was worn considerably more than the outsides. I am running Bridgestone SO3's (which I feel are really great tires) and had not run any DE or autox's on them. They have about 12,00 miles on them. The car was set up-corner balanced and wheel alignment- by a very reputable shop that specializes in track setups. Is this type of wear normal for a 930 or is my alignment out of whack? The car runs dead straight if I let go of the wheel. The struts, ball joints, tie rods, etc. are in good shape. I was also thinking it was the alignment specs but wasn't sure. I'll be calling the wrench today and see what he says. Is it possible to shave just the outer aspects of the tire to even them out, or is new rubber in my future? The rears don't look too bad so I guess I could get away with just buying fronts.

 

Mike,

Inside tire wear as you describe it is usually due to increased negative camber. It's not unusual to increase the negative camber from what Porsche recommends as an enhancement for high speed/spirited driving. However, too much negative camber can cause more rapid inside tire wear. With the S03's, you can swap each tire to the other side so the inner wear will now be on the outside, to even out the tire wear. Also a good opportunity to remove all the wheel weights and balance the wheels, which may fix your high speed shimmy problem.

 

Thanks, Bill. I wasn't sure if that was an acceptable option, but I'm glad to hear that it is. Believe it or not I am now riding on Nokian studded snow tires, and the shimmy has been eliminated. Great traction, horrible ride!