By the time the brake dust is baked into little nubs or pits there is little you can do. By then it is burned into the surface of the wheel. Even if you removed it there would be a depression that would just fill up rapidly again. Since the Chroming process weakens the wheel by over 30% you are not starting out with the best foundation. BTW, NO german manufacturer sells wheels that are chrome as OEM as they do not meet TUV standards. Someone in the pipeline had to of bought chrome wheels or had the OEM's chromed. Depending on how bad the burn marks annoy you it might be time to call Rennsport. Sorry I can't be the bearer of better news.

Hope this helps...Lee