In the past I have run Toyo M55 siped and studded for winter use. This year I switch to Wild Country XTX because they are snow tire rated without studs, which means I can use them more than 1 season.
Bother work great. The XTX actually surprised me on ice. Much better than expected. However the M55s are superior in deep/heavy mashed-potato snow.
In either case, Oregon and most western states still require chains when towing or over 10,000 pounds so if the signs are up, I chain up the van and trailer. The better stopping power is essential when stopping that much weight, and last I heard the fine was $550 if you get caught. I have seen state police pull over both commercial trucks and RVs who did not chain up.
2000 E350 extended wagon dually
V10 w/ Banks Powerpack, Diablo Predator
Buckstop Outback bumper/grill guard
Reunel rear bumper