Mike,
Speed is what the insurance people are looking at. As the tire technology
improves with better grip (chief example are the ST classes) the need for DOT
slicks becomes unnecessary. I hope others on this list more technical than I
can provide a better answer. My one thought is that the breakaway speed is
reduced thus the car speed has to be kept down in order to finish the course
quickly. Remember that Solo in the early years did NOT have DOT slicks in
the stock classes.
I have been told that the marque clubs who have started street tire stock
classes have seen a BIG increases in entries.
Jim
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