There is a dangerous myth that if a vehicle has All-Wheel Drive (AWD), it doesn't need winter tires. This ignores the fundamental physics of stopping and steering. AWD helps you accelerate in the snow, but it does absolutely nothing to help you stop or navigate a corner. Only the four contact patches of rubber touching the road can do that.
The Glass Transition Temperature of Rubber
"All-Season" tires are a compromise. They are made from a rubber compound optimized for longevity, rain, and moderate heat. However, when the ambient temperature drops below 45°F (7°C), the rubber polymers in an All-Season tire freeze. They undergo a physical change called glass transition, turning from a pliable, grippy material into hard, slick plastic. Hard plastic sliding on cold asphalt equates to virtually zero braking grip, regardless of whether you have an AWD SUV or a FWD Prius.
Why Dedicated Winter Tires Rule
True winter tires (marked with the 3-Peak Mountain Snowflake symbol) are engineered with a heavy infusion of silica and incredibly porous rubber compounds. These compounds remain highly flexible and soft even at -20°F.
Furthermore, pure winter tires feature thousands of tiny zig-zag slits across the tread blocks called "sipes." As the tire rolls, these sipes open up and physically bite into the snow, packing the snow into the tire. Paradoxically, snow-on-snow friction provides vastly more grip than bare rubber-on-snow. By trapping snow in the tread, winter tires stick the vehicle firmly to the road surface, cutting braking distances on ice in half compared to all-season tires.