I got my rims zinc-arc sprayed (which is a type of galvanising). If you take this option then there is no risk of warping, and so far I am very happy with the result. I got the rims painted by the same people that did the zinc arc spraying as they knew exactly which paints and primers would work best. So far none of the paint has chipped, and there is no rust on the rims - not even around the wheel nuts.