Brake dust and other contamination can be very difficult to remove due to the high temperatures that your brakes product, it helps bond the contamination to the surface.
As far as a wheel cleaner I would suggest P21s Gel Based Wheel Cleaner
. Its gel base allows the product to cling onto the verticle surfaces of your wheel (spokes, etc). You can let it soak for up to two hours on the wheel. If that is not strong enough for the stains then we typically recommend the P21S Finish Restorer
for wheels that need a deep cleaning. This metal polish works into the wheels surface to safely release embedded brake dust, road grime and more. The Finish Restorer is best applied with a two sided microfiber polishing towel
that really helps the polish work its best.
To help prevent this from happening again and to keep the wheels looking great I recommend applying a coat of wheel protection like the Wheel Wax
or Poorboy's World Wheel Sealant
. These are designed to resist high temperature brake dust and other road grime. It keeps the wheel looking better, longer and reduces the time you spend cleaning the wheels. Let me know if you have any questions.
George @ DI