Brake cleaner & sand paper? Sounds a little too much. I always clean the inside of the wheel.
I use Armorall Triple Action Wheel Cleaner to clean really hard stains on inside of wheel. I use it sparingly because it's very acidic.
Armor AllŪ - Product Detail
Normal cleaning which I do at least once every 3 weeks in warmer weather is P21S wheel cleaner. I buy these 5 litre at a time and it's the cat's ass.