USAC used to have a RR tire rule.

The RR you qualified on, was the one you had to run the feature with.

Case in point, the 'Fortney Sprinter'. The car was ran last at Winchester in Oct. 1979. They brought the car home, pulled the engine, and it never raced again. When the car was bought from Mr. Fortney some years back, it still had the RR on from that day, stamped by USAC with the date.