My winter wheels (the "V-spokes" that came on the car when purchased) had some stains on them from the winter as well as some heavy brake dust buildup on the inside that I could not clean off when I changed over. The metal almost looked tarnished, and it started to develop brown stains in the creases/corners. I bought a bottle of BMW wheel cleaner at the dealer Friday and WOW!!! That stuff is amazing and cheap! (5 bucks for a 32 oz. bottle) It took off every single stain and all the built up brake dust. The wheels look brand new. I highly recommend you try it.