Shelby American and Halibrand came up with a lot of different specific magnesium “pin drive” racing wheels for Cobras. The earliest sprint car wheels, a.k.a. “kidney bean” wheels didn’t have many variations and that is probably just because they were not in favor very long. The confusion today revolves around the many variations of wheels with six spokes. Somewhere back in the last few decades all the six spoke wheels acquired a somewhat inaccurate common name “FIA wheels”. They were just race wheels to Shelby and Halibrand. The 8.50 inches wide rear wheels did get use predominately but not exclusively in “FIA” events. There was not a single design of front wheel or a single design of rear wheel. The earliest six spoke front wheels won’t clear the front brake calipers introduced with the new rack and pinion steering chassis updates. In comparing five different casting patterns for 6.50 inches wide front wheels for example, there was an evolution in brake caliper clearances and offsets. The final 6.50 inches wide wheel would back fit to any chassis or any brake caliper AC Cars or Shelby American used. There were not as many rear wheel choices.
Since roughly the mid 1970s several companies in more than one country have produced their interpretations of the final evolution for Cobras in 6.50 and 8.50 widths and offsets for Cobras and 427 Cobras. Multiple interpretations of the kidney been wheels have been produced also. The versions that are missing, at least I have not noticed anybody selling new replacements, are the 6.50 and 7.50 wide models used widely by Shelby American and independents during a lot of 1963 and onward, especially in SCCA racing events in the case of the 7.50 rear wheels. Many of the most famous works and independent racers used the 7.50 inches wide INDY “500” wheels as rear wheels. I cut and pasted the image below for another thread but I thought I would put a copy in the Originality category. If one were to restore one of many cars to a mid 1963 or later until the last designs came out “point in time” configuration these are the wheels they would use. The 7.50 rear wheels were often still in use on cars using the last version of front wheels.