I have the 31" Guard Dogs and I drove across the country and back taking back roads and scenic roads as well as a lot of off-roading pit stops along the way in Colorado during February (a TON of snow on the ground). Also, I did a lot of wheeling in the mountains of Tahoe before driving back. They have probably 20,000 miles on them, still have more than half tread and they are wearing great and have taken all the beatings I could have possibly given to them. Rock, snow, mud, sand, gravel roads on a daily basis, whatever...they are holding up fantastic. But...I will say they are stupid heavy and oh man the road noise is enough to wake the dead. For the $480 I paid for them I could not be happier and I certainly plan on buying another set.
Knowing my luck, now that I said something, I'm going to have a blowout or something...