I have a set of those on my Ranger in 235/75-15's. They are a good mud tire, and are great in loose snow... but have the stopping power of skis on packed snow. I got them used too though, but they still have a lot tread on them. They howl like a banshee... which personally I kinda like for some reason.
Dunno how 31's would fit with 5" of lift, my little tires look pretty good with 3" though.
I got a new set of 255/75-17 BFG MT KM1 Jeep Rubicon pattern almost a year ago and they make a fool out of the Dunlops for a driver, much much quieter and a lot better on snow packed streets.