I've had the opposite experience with hub rings. I have always run custom wheels with every car I've owned since the mid 80's. Plastic rings deform over a period of time and you have to replace them every so often. The aluminum ones do not. I've run the same set of aluminum rings for almost 10 years on my D2. I had to have them custom made back then for about $100 a set including shipping. The only thing you do is use anti-seize on the hub so they do not "get stuck."
I'm just curious, the 57.1, that a A8 "Hub Center Bore" and the 66.6 is that like a MERCEDES BENZ wheel? I'm really just curious as to what vehicle, that's from. Thanks
Mercedes has always run a 66.56mm center bore. Audi has run 57.1 but D4 are 66.6. I think Audi is moving toward the 66.6 hub bore. Most wheel manufacturers made the hub 66.6 so it would fit both applications.
Started with the A5 and on to Q5, and then rolled back through A4, D4 A8, and C7 A6. Audi never really explained the "why." but the bearing was probably growing in diameter at the same time on the other side of the hub face.