Well with the wheels, or everything for that matter, it has to be bare metel, even is you grind it down we usually just go over it again, so if your trying to save a buck by sanding it your self i wouldnt even bother really. Besides after we strip it we pressure wash it with a hint of, and correct me if im wrong phosphurus, to keep it from rusting untill you spray it, and yes it is very much more stronger than paint and more durable, and unlike paint its alot easier to take care of, no polishing or anything just wash and go.