They're probably clearcoated. What's the condition of the clearcoat? If its peeling, discolored, scratched then the first step is to strip the clearcoat off.
There's kits available to do that. Mine cost $40. TAKE THE WHEELS OFF THE CAR BEFORE USING THE CLEARCOAT REMOVER IT'LL TAKE OFF THE PAINT TOO. You may have to do multiple treatments to get it all off. And also use nasty tools and words to help it along. I learned some interesting new strings of four letter words.
After stripping I just polished the wheels with Mothers polish. Others are good too. It's messy. I never re-coated the wheels. I just spritz Turtle Wax Ice spray detailer on them and wipe it off. Looks great. I had an estimate of $500 for all four wheels to be reconditioned. Another guy who had it done didn't think his wheels were $450 better than mine, and he had to take all four wheels off, put the car on jackstands for 6 weeks..
Good luck