My rule of thumb is to try not to drive on them when the temp is over 15. I was going to put them on last weekend but didn't get time. Wouldn't you know it I was driving back to London Friday night/morning around 1:30 going through Pickering and there was snow on the ground. Not a big deal if it weren't the first time this year. Since it was though there was no residual salt on the ground. Therefore it turned to sheer ice. Long and short. Snows go on this up and coming weekend.
