[TireNerd]
On a related note, everyone please be mindful of the temperature in relation to the tires you are running. Being the "designated tire nerd", I thought I would point out again how cold temperatures and high performance tires never mix. The reason is that when it is cold enough such that the "glass transition temperature" of the tire rubber compound is approached or passed, the compound essentially has a state change, losing its flexibility and resulting in a dramatic loss of grip.
Unfortunately, tires that can absorb massive quantities of heat and maintain reasonable wear at high levels of grip also have the highest glass transition temperatures. Tglass is highest starting with R-compound tires and the lowest with snow/ice tires. Most R-comps should not even be exposed to temperatures below 35F or so. In fact, Toyo has a warning statement they put out about how subjecting their R-comp tires (RA-1, R888) to temperatures below 32F can result in permanent damage to the tire:
http://www.racetire.com/products/bulletins/ToyoCompetitionTireStorage.pdf
Even "max performance summer tires" like the Michelin PS2, the Yoko Advan Neova, etc, will experience siginifcant loss of grip once temperatures drop below 35F or so, with performance beginning to seriously trail off as temps fall below 55F or so. This is really easy to experience with a high-torque/power RWD car as rear grip just seems to disappear taking off or shifting from 1st-2nd once temps start to fall below 55F or so when running max performance summer tires.
Tglass is the reason why we almost ALWAYS see an “instructor” car in the Armco in the first session of an HPDE at VIR when it is below 45F or so in the morning...at least at local CCA events it seems. These "instructors" seemingly can't believe what happened while the organizers just speak of a "cold track not having traction." Well, it is all traced back to a total lack of understanding and respect for the R-comp tire's glass transition temperature. Until you've driven on a tire at or below its Tglass, that internal respect is hard to have I guess.
Hence, be mindful of the temperatures at winter events...especially on that first run.
[/TireNerd]
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