I would not be able to tell you how to prepare your rims for powder coating.
My rims were painted by a company that sponsors me.
Sorry I can't help you but if you want to powder coat your rims it should cost you like $60 to $80 dollars per wheel.
By the way thanks for the complements

By the way, your car looks great!!

Hey Buitre,
I want to paint / powder coat my stock wheels to a solid black. What kind of preparation is needed for the surface so the coat will adhere properly?
Thanks,
bpoole38