I have 2 friends who run a different tire (Buckshot Mudder
) in the Q78 size that I have wheeled with extensively.
My previous set of tires was P78 buckshots. (33x10-15) I now run 33x12.50 Goodyear MT/Rs
. I rolled one of my P78 buckshots off of a 7" rim at 15 PSI once. But they did quite well in mud.
The Q78s my friends run, they typically run around 15-20 PSI. Each lost the bead once at 10-12 PSI and mow runs them harder. They both run 7" generic steel wheels. These thin tires work great in mud, and nothing
beats them in climbing out of ruts. They work well in most muddy situations as well.
The TSL/Sx is a very heavy duty tire. Many off-roaders stateside consider them the strongest offroad tire made. I have never seen on torn open on the trail. A friend of mine who runs them (35x15.50!) doesn't even carry a spare anymore, since he has run them 7 years without a flat or blown bead. But he runs beadlocks, and doesn't count on the vehicle for transportation.
TSL SX tires don't play nice on pavement. They wear out VERY fast, and are very seldom actually in balance. But offroad, they are my favorite tire. I just can't run them now because my rig sees too many street miles right now. They can flex VERY well - the sidewall lugs are broken up with cirumferential gaps to allow the tire to flex. But you must air them down lower than a typical bias ply tire to get them to flex, which means eithr you run a beadlock, or risk blowing a bead on the tire. Many of the vehicles around here running SXs run very wide tires (at least a 14.50 width) on 15x10" wheels to minimize this problem.
Basically, I would say that they are well worth the risk, because they are the most durable tire out there.
As far as not flexing, take a look at this: