The question should be: "Why does Goodyear spend money to redesign, upgrade, market and distribute their ST tires when they already have 'superior' LT tires in their product line?" What sense does that make? Why not just market their existing LT tires to the RV industry?
My theory is that ST tires are loaded at or over capacity 100 percent of the time. People boast 20 pounds under capacity for their tires and then are not towing level. Or, their tires are at capacity and they keep loading more stuff into the trailer indiscriminately. My dealer installed Towmax tires on my trailer (newbie). I have 12,800# of tire capacity supporting #8,200 pounds of axle weight. I don't anticipate any problems.