Also, Snappy is a fawking liar.
But that's okay. It's called self-deception, and we're all guilty of it. I thought my Nitto ATs (uh... Tar and Chip Grapplers??) were wearing awesome, until I went to get them rotated after about 15k and found that I'd burned 4/32s off the rears and 2/32s off the fronts. In the end, I think I got about 40-45k out of them. Not bad for a truck that usually weighs 13k, but not bulletproof, either.
I would not expect better mileage from a tire with larger tread voids, and I would definitely expect a big MT to be a fish-tailing bitch up to roughly 70mph on wet roads with that diesel turning them.