As others stated before, Sonax, applied cool works great, but I find even rinsing with a pressure washer doesn't get everything. I found that the EZ detail brush, sold at a bunch of places like amazon or detailersdomain), makes ZCP wheels super easy to clean from front to back (all the way in the back). My pre-wash steps are usually.
1) cool down car.
2) spray sonax on wheels. wait 2 minutes.
3) use ez detail brush on all wheels
4) rinse with hose
5) dry (after wash) with electric leaf blower
They always come out crystal clear. FWIW, for a while I got off Sonax, and was just using regular soap, but I think I have convinced myself that the sonax really does break down the grime better and leave me with wheels I can eat off of.
2011.5 E92 ///M3 Space Gray; Fox Red & Blk; 6MT; ZCP; ZCV; ZP2; ///M Performance Exhaust (sold)
2012 VW Jetta TDI (sold)
2002 Subaru WRX (sold)
The World in 35mm