i painted 4wheeler wheels before and i just sand blasted them and went to a paint store and got the paint i wanted. i cant remember what kind of paint it was but i do remember it had something to do with nascar and it was supost to be really strong stuff. it worked good and it didnt come off. if you sand it make sure it is sanded really good because if not it will come right off. it was a couple years ago so i cant really remember what it was. also you could also powder them, my boss power coats stuff it works really well.
-Aaron