i assume its bare aluminum and not clear coated, that being said, eagle one makes a wheel cleaner that contains amonia i believe, it kinda burns your eyes and nose with the fumes. i use it on my wheels and diamond plate when it gets crappy with brake dust and the black tarnish crap. spray it on and let it set a few minutes and hose it off, if its real bad i scrub in the same direction with red scotchbright then hose off. it leaves it BRIGHT natural looking like a bar or piece of billet. after that you can polish it with mothers or whatever if you want, i leave it as is. i get it at autozone.