The Group 2 cars raced under the rules in FIA Appendix J. In the first year of Trans Am racing, 1966, Appendix J did not specify specific wheel sizes. Appendix J simply stated that the wheels used had to be the wheels that were supplied by the manufacturer as listed in the Recognition Form approved by the FIA. The 1966 Recognition Form for the Mustang listed wheels sizes as 15 x 7 or 15 x 8.
For 1967, the Recognition Form for the Mustang might be different.
For 1967, the Recognition Form for the Mustang might be different.