Take a 50/50 mix of water and vinegar to remove any water minerals first...........Dont do in the sun however.....and try to work on cool surfaces....
Thats a good looking mudslinger by the way............!:xyxthumbs
And hats off for getting or choosing clear coated rims....I on the other hand, have some similiar to your, without the imitation rivets, and they are a real burden to keep clean...........