Hears a trick I learned from a top competitor at the Monetrey Historics: the one step tire cleaner foam. Spray it on, let it sit over night and in the morning the plastic is absolutely perfect. The key is to get the grime off the plastic first., no dressing will make dirt shine. Any brand one step tire cleaner foam for $2.95 available from any parts store or Walmart will work. It will clean the plastic and rubber and leave a low luster shine like it was when new. Meguires is great but too greasy/shiney.