In the 2006 Explorer Owners Manual it describes how to clean aluminum wheels and separately how to clean and protect chrome wheels. Since my 18" "Chrome" wheels on my Limited seem to be plastic , I am at a loss as to how to clean and protect the shiny chrome finish. The tech at the dealer said it was very important to keep brake risidue off of them from his experience on F-150'a with similar wheels but could offer no help on how to do this. He also said that if I kept the brake dust off of them the finish was under warranty for 36,000/36 months and seemed to hold up quite well. Anyone have any knowledge on this subject?