from the supps
Available Car Classes
Participants in SLRSS events can enter in all National Classes. This includes Supplemental Classes (STS2 and STU) and Junior Kart classes (FJ1, FJ2, FJ3 and FJ4).
A SLRSS only class, STO (Street Touring Other) is offered in addition. This class is open to cars with any modifications legal under the 2006 SR with the following restrictions: Tires must be STS legal (tread wear of at least 140), except that there is no width limitation, and vehicles must be licensed for street use.