need advice on tires for welding rig.

[Coalsmoke]

hi guys, I'm setting up a mobile welding rig and I need advice on tire choice. I curently have the toyo m-55 and they are ok, but I'll be lucky if I get 35,000miles out of them, probably closer to 30,000, and this is with a truck that is mostly unloaded. The alignment is right on spec and the tires are wearing great, just too fast. However, now I'll be running about 8500lbs most of the time, so I need something that wears like iron. Any ideas?

Here's a few more things about the driving I do:
- I don't care about ride quality too much, so long as they track well and balance ok, if they sing that's just fine.
- These tires see lots of different terrain. I need them in the snow, on the ashphalt, on gravel roads, and on sharp rocks. The m-55 have been great about not getting cut up, alright in the snow, and not too good in the mud. They cleat up real quick and then don't sling it back out.
-the single most important thing is that these tires don't puncture / delaminate easily, as I have to drive this truck through some pretty interesting off-road terrain to get to broken equipment.

Any ideas?

Thanks