[aerohead]

I'm okay with it in spirit.Renault did this with their 146-mpg VESTA-II concept car.I would be critical of dynamic balance.You may want to visit with your local tire providers and see if they can balance ,or check the balance of the wheel/wheelcover combo.There is probably some rpm at which the difference in mass you're creating,will surface as a vibration.At some point,with the covers being constructed of plastic,they could begin to deform under stress,potentially "leaving" the car.At that time,pedestrians,bicyclists,and other motorists will begin to think ecomodding really sucks.