I've run both the LTB and TSL and liked them both. I have never run the SX, but like the idea based on the improved side wall puncture resistance. BUT, they weigh more, and my Samurai has limited power. I'm very weight sensitive with my rig, so will probably go with a regular TSL when it comes time to buy tires. I have never run an IROC, but they are kind of balloon/wide looking in the 36-37" size. I prefer a narrower tire. I'm most likely going to end up with a 36 or 38 x 12.5 TSL with the centers of the lugs cut and opened up.
This is my opinion, based on what I have either used, or saw on the trail.
IROC great on dry rocks, weak sidewalls
LTB's kinda in line with the gumbo mudders, stiff, hard, not as much traction as the others.
TSL's just plain work. nothing bad to say about them
TSL SX's just a step above a regular TSL, lil more resilient, and has the added sidewall lugs
I had 39.5" Irocs. Best one measured like 38". They hooked up well in rock and mud but wore out quickly. Running grooved 42" TSL's now. No complaints except they miss Tellico mud.
Right as I'm considering getting some new 40 inch LTBs for my k5 because of the the price. I've ran SSRs and SXs on my jeep. The SXs are badass I don't have complaints because pain in the ass to balance, great size, and pretty soft tread for the 38.5x14.50-15s. Feel about the same weight as my 37/12.50r15 SSRs I had on here before that but much bigger.
The revised sx2's now come in some pizza cutter sizes, like 35x10 and 37x12, similar to the q78. Never hear anything bad about the sx's aside from a little extra weight.
I've had 31x11.5 LTBs on my samurai for a bout a year and so far they've been awesome. Clean out well in the mud even with the low power of the 1.3, and at 5psi on bead locks they start to flex good in the rocks. With out beadlocks I would be hesitant to run LTBs on a light rig because they didn't start to flex until about 5-8psi.
