my 31" Bighorns balanced with very little weight (less than 2oz per tire with factory alloy wheels), but I knocked them off on the trails and they started getting bad up front due to alignment issues. The rear don't have any weights (thanks to rocks), but were wearing perfectly. When I did my longarm and new tires, I threw in 8oz of BBs per tire so I won't have to worry about it.
We didn't get any snow worth mentioning last season, but the 06-07 winter I pulled my brothers car 15' up a 20* highway embankment, while my XJ was on ice. I'd say they grip pretty well. Due to siping, the other tires may do better, but I haven't run them. I do know that the Trxus MTs have possibly the weakest sidewalls of any offroad tire currently in production. Which would scare me if I broke through a sheet of ice on top of the snow.