Here is an article to describe Defender LTX more and how different from prior MS2: Meet Michelin's new LT tire: the Defender LTX - Retail - Modern Tire Dealer

Note from article:

- The Evertread compounding is “the toughest compound that we have available”....

- In P-metric sizes the Defender LTX stands up better on gravel to chip and tear resistance compared to the LTX M/S2, while treadlife, wet traction, snow traction and rolling resistance are unchanged. With the LT sizes, treadlife and chip and tear resistance both are improved, while wet traction, snow traction and rolling resistance remain unchanged.



Basically, Defender LTX has Evertread which is very tough. And this Evertread is on both sidewall and tread. I like this idea...instead of adding plies to the sidewall (and adding weight and worst ride), they apparently strengthen the actual rubber compound.