Have you tried opticoat on wheel yet? Does it help?
I had some opticoat left over and I am wondering if it works with brake dust. It is permanent and I don't want to ruin my wheels.
I havent, but only because at the time the Gtech stuff was cheaper.
Lots of detailing forums on the net have shown Opti works great on just about everything, including wheels. I wouldnt use it on glass (it will create glare) but I would feel comfortable using it on anything with clearcoat (like wheels) and plastics (like headlights, taillights, etc)
If you are really worried about it, try it on a small spot of the wheel. They key for OptiCoat application is in the prep work. The surface needs to be 100% absolutely clean of everything. Grease, dust, dirt, previous coatings, etc. Then polish it as perfect as you can get it, then clean it again to make sure any polish leftovers are gone. Then apply Opti.
One of the Optimum tech reps is all over detailing forums (his name is Chris), look for his posts and he'll have plenty of how-to and tips for you.