Over time, aluminum wheels scratch and become corroded. This is due to the alloy used to manufacture aluminum. It is softer and susceptible to corrosion. Many high-end wheel makers seal porous aluminum wheels by applying a urethane hard coat onto the surface. This prevents the wheel from becoming dull. You can follow the same process as the high-end wheel manufacturers and clear coat your wheels to make them look like new and to keep them shiny for a long time.
Sand the surface of the aluminum wheel using 600-grit sand paper to remove any scratches. This also makes the surface of the aluminum wheel rougher to give the clear coat finish something to adhere to. Make sure you get the sides of the wheel spokes and the backside of the wheel if the spokes have a deep offset.
Wipe the wheel clean using a degreaser compound like Kleen strip, mineral spirits or Naphtha. Dry the wheel using a clean towel. Make sure every part of the wheel is free of dirt, brake dust and grease.
Spray a coat of urethane clear coat finish onto the aluminum wheel. You can purchase this at most automotive part retailers. Every brand of urethane provides instructions on the container for the amount of coats needed for adequate coverage and the amount of time needed for drying. Usually, you need three to five coats with 25 minutes between coats. After that, you need three to five days curing time for the urethane to completely harden.
