Winter tires include a greater degree of softer compounds than all-season tires. This allows better gripping in cold temperatures due to better flexibility of the tire. Some winter tires maintain some flexibility up to -40 degrees Celsius. All season tires lose flexibility between the temperatures of -8 and -15 degrees.
Winter tires generally have more sipes than all-season tires. Sipes are the tiny thin slits that are cut into the tire which generally improves traction. (One study by the US National Safety council found siping improved stopping distances by 22 percent, breakaway traction by 65 percent, and rolling traction by 28 percent on glare ice.)
Grooves in winter tires are approximately 30% deeper than all season tires. This allows better channeling away of snow, sludge and water much more efficiently.
Winter tires generally generate more road noise. This is due to block shapes of the treads, groove configurations and snipes.
Winter tires are often identified by a mountain and/or a snowflake symbol on the side.