http://www.georgiapowdercoating.com/faqs/
"Q. What items can be Powder Coated?
A. Any electrically conductive metal or material that can withstand 400° F temperature without losing its integrity."
next i would look up what metals make up the wheels in question and look to see their heat threshold.
& no problem im interested myself. right now im leaning towards some type of wheels can withstand this while others cant. i know cast iron (from talking to someone about manifolds) with heat tends to expand and that rapid expansion > cold can cause it to crack hence why it was so hard to find someone to weld a mani im going to use. while this isnt used on wheels ( i dont think) its good to know which metals act different ways especially with fabrication & the money we spend on things.