My take on car tires on solo bikes------why aren't road racers using them? I am everyday rider since 1955, ridden over 1.5 million miles, BSc Safety Degree, not fan of MSF but my instructor card dated 1973-74-----in the fifties bought a kinda junk Harley WLA 45 that had 18 inch junk yard car tires=unrideable until MC tires installed----experience with MZ sidecar outfits in Germany, 15 inch Citroen 2CV tire on rear---required special rim, tube with offset valve stem, spoked with offset for clearance on swing arm-----against the law solo and unrideable solo but worked well sidecar-----cost? not cheap.