8 MacDonald and Mickey Thompson pose with the Ford-powered Sears Allstate Special. The car was built to run on 12-inch-diameter tires to lower the center of gravity and had a full body for aerodynamic purposes. But Indy officials made Thompson switch to 15-inch wheels and cut openings in the tops of the fenders to make the car a quasi-roadster. These changes eliminated the design's aero advantages and made the car unwieldy. All of the name drivers of the day passed on driving it, and several advised MacDonald to do likewise.