When I first started drag racing at the tracks in SO CA in the ealry 1970s avaition gas was offered in three grades I can remember, 80/85 octane, 100/115 and 115 /145 octane. The lower number represented the rich octane rating on take off and the upper number represented the lean rating. The 115/145 was lowered later in the late 1970s to 115/135 and finally drop all together once the airlines stop using the older piston driven airliners