Stopping in snow, where there is no tire contact with pavement, is fundamentally very hard. Any tire on braking will get tread grooves that are packed with snow/ice, at which point its only the rubber tread tread blocks that are riding on whatever surface they are one. If its snow or slush, you are effectively aquaplaning, if its solid ice, then you might have a chance if there is something about the tread blocks that works there. Good winter tires, like AWD, will help you control the car and get it going in sticky situations, but it will not help that much in getting it stopped beyond a certain point.

 

I'm curious to know if a C4S fitted with all season tires (like the contis) will pass muster with Caltrans in California for highways under chain control? Anyone have experience with this? I do a lot of trips from San Francisco to Tahoe in the winter. I never thought of taking my P car to the mountains, but sometimes I am tempted, and if I could get past the inspection station, I know I can negotiate the snow on a plowed road with adequate ground clearance.

 

As I was from Truckee with my C4S with my 18s Pirelli snowsports, I can say you will pass! 4 is for the rain in SF?