Yeah, your missing something. The mtr has half of the tire with at like tread and the other half has a decent sized void for mud. They are a great tire for rock but my km2 has out performed them in most types of mud and I think go just as good in the rock. Mtr is quieter on the road though. Where do you wheel? That's the biggest thing about picking a tire us the terrain you are using it in.
The creepy crawler is a great tire. Tough sidewall but you have to air down to 5 psi before you start to see sidewall flex. They actuall rode great on the road after they warmed up. I sold mine and went back to the km2 only because the bias tire was wearing out very quickly.
i have 35 xterrains on my DD/TR toyota. i think the 37in flavor are 13.50 wide. i think there great for a DD that gets wheeled hard on the weekend. in all honesty, as i have no reason to lie, i have about 22k mi on mine and got about 1/2 tread or maybe better. i have to keep them rotated often though.
I've got over 1k miles on my 38.5" bias Creepy Crawlers, and so far they are wearing well (barely noticeable actually). They take a couple miles to smooth out, but they run fine unbalanced up to 65mph. Handling/braking/etc are good for what they are.