I have a 98 528 and just replaced the stock 15 inch wheels with 17x8 front, and 17x9 rear running 235x45x17 on the front and 255x40x17 on the rear. No noticeable shimmy as of yet. I'm really glad to get rid of the stock rims. BTW, I went with a set of OEM style 32 radial spoke wheels as I was reluctant to use centering rings, I wanted the OEM wheels that were built for my car. I would have all wheels checked for balancing and trueness before doing anything else. Heres my story. I have a new set of Yoko A520's on 4/ 17x8 MilleMiglia rims. The size is 235/40/zr17 on all 4 wheels. The problem is - - I have a noticeable amount of Trammeling/Steering wheel shimmy, and I have been told by the BMW dealer that to run 17" wheels, the correct tire size would be 225/45/zr17. I was ready to go out and purchase 2 new A52O's in that size, however they are not available. The next size is 215/45/zr17, smaller than what stock is. I DO NOT want to have to buy 4 new tires, but I need to do something. Can I put 215's on or should I get a different brand of tire (need suggestions) just for the fronts in the correct size of 225/45/17? Any input helpful!! 97 z3 1.9