Wheel paint is quite durable. I used it to paint the frame, fork legs, swingarm, and misc small parts on my 03 KDX220. I'll post pics whenever I can log into my Photobucket account again!
I used both dark gray and silver Duplicolor wheel paint on my bike. I have used Plasticoat wheel paint for a few other projects (truck wheels, bicycle frame, bumpers, etc). No comparison, go with Plasticoat! It's far thicker and more durable than the Duplicolor stuff (which seemed more like thick spraypaint). The Plasticoat seemed like a hard plastic coating, just like the name suggests.
My truck wheels held up to off roading, Michigan winters, and impact driver slips with hardly a mark. I once accidently grabbed the can of black to use as a guide coat on a car I was painting. It was horrifically difficult to sand off. I think sanding the knobs off your tires would be easier!