[Karl Bebout]

"Vehicle dollies" might do the trick for you. They are concave platforms with four casters each that you set your wheels on. The casters allow you to push the car around in any direction. I think that Harbor Freight sells them for about $60/pair and Parts America has them for $50 a pair. They are "647008 Wheel Dolly" at P.A. your can order from either on line.