...
I have only two areas where the SCTA rules give me pause. One is tire speed limits. We would like to use our list of limits rather than the SCTA list. They're mostly not that dissimilar, but it would mean that (as an example) V rated car tires would be limited to 155. The other area is brakes and stopping. Because of the start line and timing locations we have to use, we have about 4000 feet of stopping distance, with about 600 feet of dirt after that. Cars with the usual (poor) LSR brakes can use chutes. But is a fast LSR bike with no front brake going to eat dirt before it gets stopped? You would know better than we would. But right as of now I'm leaning toward requiring front and rear brakes on all vehicles. ...
Here's what I learned about tires:
I sent in two popular makes of performance tires for dynamic testing (>$800). One was a V rated Toyo (32" dia), and the other a W rated Kumho (25").
I had run both to a top GPS speed of 181, and many passes at 160+ in a 6,200lb truck (at the time) before the testing.
The lab could only run them to 215mph even though they told me they could run 225mph. They were told to accelerate them to max speed, hold for 5 miles, coast, then let cool for an hour, then run 3 times. What they did instead was run them up to 38? miles, and didn't cool them down. Load was 2200lb.
What I saw on the video was that as the tire heated up at max speed, first one flat area formed. Then another, then another. When the flats came around to the start point, the tires failed. They looked like hexagons.
The lowly V-rated tire endured 6 passes, then at 215mph and 2200lb, at 38? miles, it "chunked". A piece of tread flew off, but the tire remained pressurized.
The Y rated tire only survived 3 passes, and at 11 miles it grenaded. The carcass looks like an big orange peel.
So while I do trust the V-rated brand at 215mph on the long course, the W rated is questionable for a heavy truck.
What did I learn?
Don't trust a testing lab to do the right test. You should be present.
A large dia tire will take more speed.
As the heat builds up, the tire deforms more and more until it fails. Neither tire failed in a relatively short distance.