opticoat the wheels, best thing for BMW wheels, and other wheels! Im starting to offer it to all my clients now since clean up is SOOO much easier from then on! No more sonax is needed!
Take wheels off
sonax and let them soak for a while
agitate and rinse
clay and clean whatever else didnt come off
allow to dry before touching and re-installing (two min)
future washings should be done with just soap and water from then on!
if super bad, meguiars wheel brightener would/should take care of it, but use it sparingly as its an acid. Dont spray on a dry wheel, dont leave it on too long, dont let it dry! Spray on, let dwell for 30 seconds, work it and remove the brake dust, rinse off thoroughly, re-wash with a regular shampoo to neutralize the acid