Cracking is what happens to old rubber. Lots of things can do accelerate it. Temperature variation, sun exposure, etc. Tires just get cracked with age. And extreme cold would make those cracks happen sooner. When I got my Roadster it had ~7k miles on it but was ~5 years old, seems to have been kept ouside a lot in New Jersey, the tires had tons of tread depth but they were cracked, and when Tesla saw the car they recommended that I replace them immediately and even made me sign a waiver before they let me drive it away. I took it to America's Tire soon after since they're next to the Costa Mesa service center, have experience with the car and were offering much cheaper prices (~$800 for all 4 tires, about the same as TireRack at the time).
People think this is what happened to Paul Walker too. The car maybe hadn't been driven much and despite plenty of tread it had small cracks in the tires, which reduced their performance, and thus made the car go out of control at the wrong time. Add this to a car which is famously prone to snap oversteer (as is the case with MR cars....like the Roadster), high speed and trees on the outside of the turn and you've got a bad situation. I definitely had an easier time kicking the back out on those old tires....which I sort of miss, haha.
So yeah. Extreme cold and extreme hot will age your tires faster, and it could be that <14 degrees is a magic number that does instant damage to them (I wouldn't know, I'm from SoCal ;-)). If you daily drive the car it probably won't be much of an issue, since you're replacing the tires pretty quickly anyway, much faster than they can crack. But it's something to consider, and especially something to consider with "weekend cars" that don't see many miles and thus will have deep treads but old rubber. Tires probably shouldn't be on a car more than about 5 years in any circumstance, except maybe covered in a climate controlled garage with a humidifier in it and a guy who shines the tires with rubber treatments routinely or something, haha.
