Dunno, it's intuitive to
say that, but actual instrumented tests I've seen have not borne that out. ie:
60 mph braking on snow, Minnesota
Snow tire 362, All season 421 (advantage 59ft for the snow tire)
60 mph braking, wet track, Phoenix in May
Snow tire 181, All season 215 (advantage 34 ft for the snow tire)
60 mph braking, dry track, Los Angeles
Snow tire 155, all season 131 (advantage 24 feet for the all season)
http://www.edmunds.com/car-reviews/features/tire-test-all-season-vs-snow-vs-summer.htmlSnow tires had 3X the advantage on cold snowy pavement than all seasons had on warm dry pavement, and were actually better rain tires than all seasons.
Now, it probably depends somewhat on the tire, but I've seen basically the same result from Car and Driver with a different brand than Edmunds used.
Of course, as long as you don't run them that hard. Strafing the apex's and burnouts will certainly shred them faster, but I ran snow tires all year for a long time back in my student years and had them last from 60,000 to 120,000 km.