All-season tires are made out of a hard rubber compound to promote a longer tread life. When the temperature drops outside to below -7 C, all-season tires tend to lose traction even when the road is dry. If you need to stop on the quick this could lead to an accident. Snow tires are made of a softer rubber compound to remain flexible in colder temperatures. This provided traction and grip where all seasons tires may fail.
Most all-season tires have tighter tread designs compared to winter tires. When the tread designs on your tires are tight-closed this can result in snow becoming packed in the tread. This can reduce the all-seasons tire grip to practically zero. Snow tires have more aggressive and open tread designs to improve stability and to clear snow and slush from the tread grooves.
Grip is critical when it comes to tires. Not only to avoid getting stuck, but to ensure that your car can stop and steer. Life-saving technologies that make our vehicles safer; such as antilock brakes, electronic stability control and all-wheel drive cannot do their jobs if your tires cannot maintain grip on the road surfaces.