Dupli-Color has a wheel painting kit for wheels. It comes in a varity of colors. Its pretty simple to do, I did mine in 2 hours. First get you some 3M Scotch-Brite and get as much of the clearcoat off as possible. If you dont have clearcoat, still try and scratch em up good so the primer will have something to stick to. Next, tape up the tires(unless they are off the tire) and put bout 3 coats of sandable primer on em. After they dry, scuff em up just a lil but with that Scotch-Brite pad. Then, use the Dupli-Color wheel paint and it recommends using 2 light coats(wait 20 min. between coats) followed by a medium coat.
I was really impressed on the way they turned out. It gave my truck a more of an "offroad" look. I dont like anything too flashy anyways.