I have these on my new Suburban beach fishing rig. 285/75/16. Put 120 miles of steady sand driving under them over the past couple of days, they don't do all that well. Had to air down to 18F/20R to keep from digging down in the thick sloppy stuff. They just kind of churn through, like mixing cookie dough. They eat up a lot of HP compared to smoother treads.
Well, considering that true sand travelers (Ie. desert explorers) tend to use all terrain tires or specifically engineered tires for desert travel. Also, obviously, driving on sand requires lower tire pressure. 15PSI is close to the standard for sand travel, depending on your speed of travel, condition of sand, and your tire choice. That being said, the Duratrac should really be considered an aggressive all terrain tire. It can handle just about everything predictably well. It's not a mud, sand, winter, or performance street tire, but it'll do well enough in nearly every one of those conditions with the knowledge of the tires limitations. Every tire, as well as every vehicle, has limitations after all.
I like to defend these tires because in my opinion I haven't found or driven a better all terrain tire.