First I'd try Nevr-dull.
If it's aluminum any aluminum polish should help. If its really bad you may need to sand with 400-600 grit sandpaper then move to polish. Should be able to make them shine similar to Chrome. Finish with a good coat of wax and rewax a couple times a year.
never dull wadding polish if it isn't too bad, I got into some heavy salt a few weeks ago and had to get on my knees and get my fingers black, this is on a stock aluminum rim.