Galvanic corrosion between wheels and rotors.

[Xsbank]

Its not galvanic corrosion, its definitely aluminum oxide. The best solution is antiseize because the paint will not keep water out of the interface and its the aluminum going anaerobic which cannot be entirely stopped. you have all seen aluminum corrosion under paint, maybe even on your winter wheels. Damage the paint coating, water gets in and away it goes right into the casting. The only way to stop it is to remove all the corrosion chemically or mechanically before you repaint.