I bought a MY03 used last summer that had 17" BBS (LM) rims. Now I need to replace the rear tires and I noticed that there are two different rear rim sizes on the car--both are 17in. diameters but one side is 8 inches wide, the other is 8.5 inches (the fronts are both 7.5 inches). I guess I'll have to replace one of them, but which one?

A related question: I have noticed a vibration in the car above 70mph--kind of pulsating. Could the different rear wheel widths have anything to do with this? Could I have damaged the rear end or something running these wheels? The car has 14K miles on it. Any advice is welcome. Thanks. -El Brujo

 

Different tread width is perfectly fine. Your vibration can be many things(slow leaks, tire balance.....etc). But it is probably not caused by different tread widths.

 

Just to clarify - the wheel is wider, not the tread width. The contact patch should be very close to identical. You never want to have contact patches that are significantly different on the same axle - that's just asking for trouble.

In this case it may not make much of a difference that the wheel is half an inch wider.

 

Oh...different size on the same axle? Sorry, I misread it.

Of course it is a very bad idea.

 

Get it fixed!!!! and go with the 8.5".

 

Having different widths = having different weight on both sides which is bad.