Not coated perfect. Then this is what i did at my detail shop.
1. Get some aluminum trailer cleaner acid spray you mix with water. Mix in spray bottle.
2. Wash the rims with a srub brush(plastic not metal) or pressure washer. Rinse
3. Spray on the trailer cleaner(acid water mix) and wait for it to turn white and foamy. Then rinse with water and repeat if necessary. They will turn kinda white looking when really cleaned with the acid mix.
4. Now get on it with the mother's aluminum polish. Those bastards will come out really nice.
Used to charge $100 for that service and did a lot of them.