Matthew Fortner wrote:
Chuck Branscomb wrote:
996TT would be fine with real snow tires. Summer performance tires have a high glass transition temperature, so in anything under 40F they can be nasty and only becoming more and more worthless as temperatures drop toward and below freezing. Any car on summer performance tires is profoundly dangerous at low temps...often learned the hard way by many.

Great info. What suggestions/perspective would you offer regarding our Feb. events?
Just be aware of the rapid fall-off in grip as temperatures fall below ~40F (fall off starts from even higher level, but picks up quickly falling below mid-40s),
especially if wet. The more sticky the tire (from summer street tire toward stickiest R-comp), the higher the glass transition temperature. Note that this "glass transition" region is like a phase change of the tire compound over a temperature range of maybe 15F or more wide. By the way, Toyo even has a warning out about storing and using their R-comps in freezing weather (rubber can fracture from its brittle state):
http://www.racetire.com/products/bulletins/ToyoCompetitionTireStorage.pdf
Take extra time to try to get heat in the tires and check grip levels where you can test it safely. If temperatures are going to be close to freezing, be really careful with most all R-comp tires as the tread compound may/can be very hard when temps are in/below Tg range.