Mine are black cosmos. I occasionally polish the wheels ie every six months or so and hardly ever need to use any wheel cleaner brake dust just falls off. Are you wheels a little rough? Very strange the dust should stick so firmly.also why is so much dust being made are your brakes ok? Not seizing?a proper paintjob should help but if my black wheels are dirty its just as obvious as on silver wheels to my mind as the lovely shine goes dull!