The issue with spraying the wheels with a hose or pressure waster is you will exacerbate the brake dust issue. It's not brake dust that will end up on the wheels after this. It's oxidation from the rotors. The way in which I mitigate that scenario is by immediately spraying the rotors with honing solution that I use on my hand tools - chisels, plane irons, etc. HoneRite. I spray each rotor immediately after washing that wheel. Works like a charm.