P21S is a really good wheel cleaner. Expensive but it works on every type of wheel.
My steps to wheel cleaning are:
1. Degrease with Sonax or P21.
2. Let sit for about 10-15min.
3. Break down the wheel cleaner with an all purpose all material safe brush (for harder grime contaminants use a claybar).
4. Pressure rinse the hell out of the wheel.
5. Wash with a nice car shampoo and designated wheel mitt.
6. Dry with a designated wheel towel.
7. Seal and wax the wheel with a wheel sealant or designated wax. (Poorboys makes a very nice product for the money IMO.)
Whola, brand new wheels . This is at least what I used to do for my M3 and S2000. I have to realize sometimes that this IS a truck. Some may see my steps a little redudant, but its from a detailers perspective and gives the awesome results everytime.