the rims are powder coated, so they are not porus like painted rims, just use a strong cleanser, I don't recomend acid anywhere near alluminum rims, if you have a scratch the acid could corode the metal.

there is a chemical company called "Hydra, it has a 3 headed Hydra on the label, you want thier product called Sprint, which is a tar and grease remover, basically a chemical surfactant and when sprayed on the powder coating will remove all junk, they sell it to the photo industry and at porche dealerships.