I am just wondering. Can you use mud tires like Mickey Thompson Tires (http://"http://4wheelonline.com/Mickey_Thompson_Tires.1724") for towing?
Depends what you are towing and I suppose what they are on has some factor in it. There will be a load rating at "X" psi on the tires, the DOT (and the tire manufacturer) thinks that you shouldn't exceed it.
Yup. They make off-road trailers that use A/T or M/T tires on them.
https://www.google.com/search?source=hp&ei=Q8-hWsHXIY-0ggfLy4WwDQ&btnG=Search&q=offroad+trailers
As bodyman said, keep within their load range as you'd do with a normal ST or LT tires and you'll do fine.
If you upsize the tire's load rating (Say you went from a ST "C" to a LT "D or E" to get enough load rating), make sure the rim is designed to hold that much pressure (C=50psi, D=65psi, E=80psi generally) or the tire is rated at the proper load at a lower pressure than the sidewall.