Originally Posted by OzDriver
Brake dust varies depending on the type of brakes, but usually includes carbon dust, iron particles, and adhesive residue. At high temps iron carbide can form, and it is an extremely abrasive material (it is used to surface cutting and grinding tools). The carbide can erode the clear coat protection on alloy wheels, allowing the iron particles to galvanicly corrode the alloy - resulting in pitting.
I never had this happen to any other rims. Anyone else have pitting on aftermarket rims? I would think that these wheel companies make the rims to resist this pitting.