I run Goodyear Duratracs year-round on my 3/4-ton Suburban. Just replaced the set, had 50k miles on the first set, and about 20k of those miles were heavy towing. There was still about 4-5/32" of tread left, but I didn't want to go through this winter with that little tread.
According to the Tire Rack site, "Wrangler DuraTrac light truck tires are branded with the three-peak mountain/snowflake symbol (3PMSF) to identify they meet the industry's severe snow service standards."
All I know is that they make the truck just about unstoppable in bad weather - snow, rain, etc. I bought them first and foremost for winter driving, not caring about how long they'd last. The fact that they lasted as long as they did, considering the life/duty cycle they've seen, was a pleasant surprise.
Funny story - we were down in Gulf Shores a few winters ago. My neighbor comes up to me and asks me about the "snow tires" on my truck. He couldn't believe I run them year round.
