I think you will hit a bump or turn hard and the sidewall will flex enough to rub and grab the tire at speed. I think you are talking about mounting them to the spindle and then cutting out a bottom chunk for the contact patch of the tire. The 1969 Plymouth Roadrunner had some promo discs that worked that way just covering the wheel and none of the tire. I don't think this would work on a car w/o a stationary spindle but there are some spinner type wheels that use bearings to create a stationary center piece rather then the normal spinning center piece. here is the Roadrunner in action