Due to some pot-holes on I-77 I had to find some rims for my 98 A6. In looking around I recall the RS6 rims could be used on the A6 but not the other way around. There may be some offset differences, but I believe it is related to the size of the brake system (rotors and or calipers), ie the RS6 has a larger braking system so the rim have larger internal clearance. I have 9 spoke wineglass rims. I ended up getting two reconditioned OEM rims from a wheel shop in the region. That worked out good.