Just use soap, water, and maybe some wheel wax. I recently had to replace one of mine because I curbed the hell out of it, and the lips of the 3 old ones (2 years old now) match the new one exactly. No fading, rainbowing, or anything. Soap and water... no harsh wheel cleaners.

 

ok well i'm thinking about getting some volks (probably te37s) but if I decide on something is P21s safe? The OP said he just used soap & water and he had problems with his wheels, but all I use on mine are P21s.

 

have you given any thought to the fact it might be your water causing the issue. I live in FL and the water here is hard and leaves a lot of spots and god knows what else. I bought a spotless water system that uses a resin based system and I swear by it. Best part is I can wash and walk away even in hot sun and NO spots.