I've mostly had BFG muddies (on suzuki's, land rover shorties & my 80 series). on my 80 I started to be more particular about them and rotated them every time I did the oil & filters so every 5,000k's .... all 5 tyres were used in the rotation and every 20,000k's i had them stripped and flipped around on the rims as well.
The car weighed 2,850k's (front & rear bars, roof rack, drawers, dual bat's, winch etc...), it got used around Toolangi and in the High country a lot yet I got over 90,000k's out of the tyres though, while they were roadworthy they weren't much chop in the mud.
I was always very happy with their road manners both for handling and noise.
I'm sure the same care shown to other tyres would give a similar result but directional tyres (some of the Mickey T's?) mean this is not possible
I am about to put some tyres on my Disco and will be going KM2's
I hope that helps.