I got 15" aluminum wheels on my 78 f150. They're only a couple yrs. old but the clear coat didn't really hold up to the Pa. road salt. Most of it is gone or flaking off. The wheels are staind with black and gray splotches but no pitting. I've scraped the surface junk off and hit them with steel wool and polishing compound with no effect. Any ideas I could use at home or should I just take them to a polishing shop?