get a drill ball and use some metal cleaner polish.

but make sure to use armorall wheel protectant after you get them clean, its the best shit money can buy...... if you spray them down good and let it get good and dry for a whole day, your wheels will stay clean. I used the stuff on my offroad toy and even muddy clay water wouldnt stick to the rims, it just beads off. Easily one of the best products ever made for car care.