I just got my 02 M5 with the stock rims on it yesterday and love it. However, I noticed that my rims had what it looked like to be brake dust or dirt deposits in a droplet looking form that was dried. No matter what I tried, they would not come off. Can anyone help me with advice on how to get these off? Are the stock rims polished, clearcoated, etc.? I used bug and tar remover and goof off to no avail. Is there some kind of rubbing compound or solvent that would take these off without damaging the wheel?