Brake Dust

WHY YOU SHOULD CLEAN BRAKE DUST OFF YOUR WHEELS EVERY TIME YOU WASH YOUR CAR - AND HOW TO DO-IT-YOURSELF!
Brake dust deposits not only look bad, but they're also harmful to the wheel itself. If left on, the corrosive nature of the brake dust will corrode the clear coat over time and actually eat into the aluminium alloy wheel surface leaving large pits for which there is no practical fix.

HOW TO GET RID OF BRAKE DUST, DO-IT-YOURSELF& SAVE!
Make sure the wheels are cool. Wheels absorb heat from the braking process. Allow the wheels to cool off and do your cleaning in the shade.
Rinse the entire rim to remove any grit that may scratch your wheels during the scrubbing process.
Spray the entire rim with wheel cleaner that's safe to use on your wheels and allow to soak for 60 seconds. Be sure to spray into all of the nooks and crannies where brake dust accumulates.
After the cleaner soaks for the allotted time, take a soft bristle brush and lightly scrub the surface. Select a brush that fits into all of the recessed areas.
Rinse off the wheel cleaner immediately after you have brushed the brake dust loose. These cleaners are extremely strong and may affect the wheel's finish if left on too long.
Dry the wheel immediately to prevent water spots. Minerals in some types of water will etch into a wheel as easily as corrosive brake dust.
Applying a coat of paste wax every six months provides excellent protection against brake dust pitting your wheels. It also makes them easier to clean.
Don't forget the inside surface of your wheels. They get the bulk of the brake dust build-up and can be easily seen with open spoke style wheels.
What you will need:
Wheel cleaner
Clean towels
Bucket and sponge
Hose and nozzle
Shady area
Liquid wax
Soft bristle brush

source: supercheapauto