Originally Posted by springbok
Yet another example of why wheel cleaners are such a no no.
They should only be used if absolutly nessesary (unfortunatly everyday in my business
). Always make sure the wheels are not warmer than their surroundings (ie let them cool after a drive) and never let the wheel cleaner dwell*, spray on, agitate and get it off asap. Remember that "acid free" wheel cleaners may be a strong alkaline and they're just as bad if not worse on your wheels, they oxidise bare alloy very quickly.
However, try polishing (or compounding) the white mark off your wheel. Some residues are very stubborn and look a lot worse than they really are. If they're non-clearcoated matt black the stain could be anything really, even something you ran over.
*manufactures state that you should let the wheel cleaner dwell for 3-5 mins on average but also state that they may damage you wheels as a get out clause. In their defence people expect too much from "safe" wheel cleaners and at the same time don't take enough care with strong cleaners.