The best thing to do is give them a deep cleaning first.
- Rinse with water to remove lose dirt
- Use a non-acidic wheel cleaner such as Griot's Garage Heavy Duty wheel cleaner.
Let this dwell after spraying for about 3-7 minutes (not in direct sunlight)
Make sure you spray the wheels and barrels generously. Don't be alarmed if you see a skim of red/corrosion occur on the steel rotors. The minute you apply your brakes this will disappear.
- After the product dwells use a bucket filled with water and a car-wash concentrate. To agitate the wheels, I use various sized Wheel Woolies. IMO these are the best at cleaning wheels and the wheel barrels.
- Once clean, rinse the wheels with water.
- Dry with black Micro Fiber Towels. (I say black because you'll never confuse these for the same MF towels you use on the paint).
- Once dry, my suggestion is to go with some kind of semi-permanent nano-glass ceramic coating, such as CarPro CQuartz DLUX, or McKees 37 Nano Glass Wheel Coating, Optimum makes a wheel coating as well...There are many nano-glass coatings on the market, do you home work. Follow the manufacturers instructions at application, application temperature and cure times.
Once the coating is cured, any future cleanings will be very easy, a quick rinse, perhaps a light agitation with soapy water (car wash soap) and a Daytona Speed Brush. Blow dry with a leaf blower... or wipe down with your black MF towels and favorite QD.
While all of this wont prevent dust from the brakes, it will make maintenance and cleaning much easier, while protecting the finish of the wheels. If you want to get the entire wheel, you should remove the wheel, polish the barrels and coat. A detailer in your area may provide a "wheels off" service.
Hope all this helps!