I don't know if you've ridden in a rig with tires like that before, but if you haven't, I suggest you do before you buy any. A buddy of mine had a set of 39.5"'s Super Swamper TSL's on his 87 chevy. They were bias ply, LOUD, didn't go down the highway straight, were impossible to keep balanced, and rode like hell. Now if this is a strictly mudding machine, you can't beat them. If you can afford it though, get the radials. It's also gunna cost you a pretty penny which ever way you go, and they wear down super fast if you drive them on the pavement much. The same guy was running 35x12.50 BFG mud terrains before the swampers, and those were nice tires. Not loud, wore pretty good, quiet and stayed balanced. Just some stuff to think about.
Swampers are great in the mud, clay,and they look really cool. I don't know what the snow is like where you are located, but here in Washington they do alright unless you are in the hills. The best prices I have found is through 4 Wheel parts wholesalers. 38.5/14.50X15 $218 a tire for the TSL-SX $209 for the ssr radials and $288 for the tsl radial their number is 1-800-421-1050 use the order code 912 they say if you order by phone they pay the sales tax.
Although I dont run swampers or boggers on my vehicle my friends do...I guess you could say we are lucky we live about 20min away from the factory where they make them so any size tire is abundant and at wholesale price if you goto the factory