Best thing ive used for those CHEAP AFS aluminum wheels is 1500 to 2000 grit wetsanding....... depending on how bad they are, start off with 2000 grit and if that works use HEAVY METAL POLISH RED, GREEN, then blue and theyll look like new GAURANTEED, i just did it 2 days ago, and it took less time than sitting there trying to rub teh black spots off