Does anyone know whether the Corona wheels typically have a painted or coated surface or are they just polished aluminum? I am trying to determine if I should use a product like "Mothers Wheel Polishing Kit" to try and clean up my Coronas that I picked up at the pick-pull yard. If anyone has a better idea on cleaning up these wheels and giving them a polished look without stripping them down and starting from scratch, I sure would be grateful!