A lot of them have a clear coat finish of some sort, I think, so you have to get through that to get at the actual aluminum. I've done that - more correctly, had a wheel-polishing guy - do that on a couple of sets: Alcoas for my Dually, which had been tarmished, and some 200-S Americans. That was many years ago, and wheel polishing may be hard to find now. But the guys who polish big rigs might handle it.