I've got a vibration around 70 MPH that seems to be getting worse, and one suspect is the tires -- I think they may be cupped due to a worn out control arm a while back. Since I'm not 100% sure there is anything wrong with them I am hesitant to replace the tires, which have lots of life left in them otherwise. So I'm thinking I should pick up a second set of wheels and put new summer tires on them, and if the problem goes away with the new set I'll replace the tires I have with winter tires, otherwise I'll have a spare set. Anyone have an extra set of OEM wheels that fit the RS6? (They don't have to be original RS6 wheels, just something from Audi in 8x18 or 8x19 that definitely clears the front brakes.) If not, any suggestions on which wheels to look for? (What 8x18 wheels from newer Audis fit?) I'm not really interested in aftermarket wheels because the nice ones are too dear and the cheap ones are too soft.