Living in a cold climate, the 7C number bothers me a lot. During the winter months my car is stored because of the salt, sand and higher risk of accidents. However come mid-march when winter is hopefully over, the car goes back on the street.

From mid march until mid may, there will be many a day where it will be nice, but where the temperature will be less than 7C, especially in the morning and evening.

Last spring and fall I did some experimentation and did find that traction is reduced fairly dramatically in these cool, but above freezing temperaturs (2/3C). Very noticable when coming to an aggresive stop and feeling the ABS kick in.

At one point I called Michelin and asked them what was the acceptable temperature range of the PS2's. They could not answer me, other than to say they should not be used in the winter.

There is no question that the tires work better at warm temperatures, but from experience, the car/tires are safe above freezing as long as you don't push it. Maybe it is my paranoia, but if the temps are below 7C, I drive the 911 as I would my winter car leaving lots of room for things to go wrong. So far this has worked well with no white knuckle moments.

I would be interested to hear how many UK drivers drive with summer tires all winter long. Having lived in the UK, I know that winter has many a cold morning. My friends in the UK that have 911 seem to drive them with summer tires and don't think twice about it.