A: Apply specially-formulated wheel cleaner with a soft-bristled brush, thoroughly scrubbing the surface of the wheel. Do not use a wire brush of any sort. Repeat as necessary until the surface is clean. Depending on your type of wheels, it's possible that some of the pitting and discoloration may have been caused by a breakdown of the clear coat on the wheel surface, allowing moisture, brake dust and road debris to directly attack the metal finish. In severe cases such as this, restoring the finish may require more involved treatment such as glass beading and reapplying the clear coat.