Those are Interco Super Swamper Boggers. if your on their website check out the SSR radial, a lot of people around here run them and love them. Another one that i like(and run) are the Mickey Thompson Baja Claw radials. on my truck in the pic.
Cummins 4BTa, 3.9L, bullet proof, plenty of upgrades avaliable, mechanicaly controlled (no computer needed to run) has the same bellhousing bolt pattern as the older GM V8 gas and diesel engines. just my .02.