The AA/GS 5.70 index class at Indy

[Ron E]

Does anyone know why they can't produce a decent RT? The average RT is around a tenth and a half. They are tire limited, but not that much. (13" wide?). Small front tires, The type car and the power available would seem able to go red on a 4tenth tree. What's in the rules to make cause these RT's?
Otherwise, a cool class.