“Currently the USAC national midget series offers the same two tire compound choices”

Not sure what USAC midgets tires have to do with local Sprintcar tire rules but USAC’s rules are the following, unless they have also changed?

-USAC Midgets-
D. National Midget Tires (LF- D12, D15) (RF-D12, D15, D20) (LR-D12, D20) (RR-SP2, SP3)

-USAC Sprintcars-
309 Tires
A. Hoosier 105/16-15 MEDIUM, 105/18- Hard and F-85A are the only approved right rear tires.