The Stock and Street Prepared tire rules have a clause requiring that
the tire model be available in 6 different sizes including 4 different
wheel diameters.
The Street Touring tire rules state that the Stock class tire
requirements all apply, except for the part about the minimum number
of sizes.
Some tires exist that meet the Street Touring requirements, but not
the Stock/SP requirements because they are not available in the US in
6 different sizes or 4 different wheel diameters.
I noticed that the Street Tire rules in the SFR supplemental rules
says that the tires must meet the Stock requirements and have a 140 or
greater treadwear rating. They do not negate the requirement for the
minimum number of sizes, unlike Street Touring. Therefore,
intentionally or not, the Street Tire supps as currently written
exclude tire models that are legal for Street Touring.
I think it would simplify the supps if they simply referenced the
Street Touring tire rules, unless the difference is intentional. Is
it intentional?
An example of the tires that are affected is the Yokohama Neova. It's
made in many different sizes in Japan, but only two sizes are DOT
approved, 195/50-15 and 225/45-16. Treadwear is in the 140-160 range,
I think (definitely at least 140). They can be purchased through
Lotus USA. It's supposed to be a really great street tire for street
use: good rain traction, light weight for a smoother ride on
lightweight cars. It's probably what I would want to replace my
street tires (which very rarely get used for autocrossing) with when
they wear out, if I didn't consider SCCA legality as part of the
decision. In fact, I probably won't consider SCCA legality, since my
street wheels are already the wrong size to be SCCA stock legal. But
other people might.
--
john@idsfa.net John Stimson
http://www.idsfa.net/~john/ HMC Physics '94
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