for any value it holds....
i've ran geolander at/s in 37x12.5x18, in D ply but w/ a load index if 123 I think it was.... my rig is a f250 powerstroke, and it was simply too much rig for those tires. they were sloppy in corners allowing a lot of wallow. however, they gave superior mileage compared to anything else I've ran. they were whisper quiet, and they wore like iron. I gave up trying to run the tread off and sold them.
i've ran STT Pro's in 37x12.5x20's- and if i had to choose one model and make of tire for the rest of my life (and that truck), that would be the one. i wore off about 1/4 of the tread in 25k miles or so, but scalloped them badly when running out of balance front tires- didn't take long, either... less than 1k miles... they are super tough both tread and sidewall, easy to balance (except for the fact my rims require stick on weights that deep mud relieved me of- hence the out of balance) and weren't too terribly loud. but, alas- to thine own self be true- I don't spend enough time off-road to rate replacing them.... by the way, i moved the front to the back and the scallops smoothed right out... damn good tire.
i now run procomp AT sports- taking a bit of a gamble because i wanted a true AT tire in E ply 128 load index- and i couldn't be happier, surprisingly. they are quiet, are wearing well, and have done exceptionally well in the off-road i've had them on. my mileage increased from a total range per fill of 1400 (STT Pro's the worst) to about 1650~1700 (ProComp AT Sport) which is still down from the geolanders @ 1800ish miles per fill. now, they didn't like the wet snow- had to go 4wd to grip sufficiently, but still better than the geo's, better than nitto tg1's, nowhere near as good as the STT Pro's (which were 'sposed to be horrible in snow)... overall, it is a fine selection you may should consider- it is made by Cooper now (along with at least 80% of ALL off-road tires). the carcass is solid, the sidewall plenty tough, and as I said they wear and roll right.
anyway, my .02...
