When the china ST specials show signs of failing I change them to LT tires. ST's don't last period.
I've had Cooper LT's D rated (65 psi) in a AP tread on my work trailer for 5 years and they are still going good. At 3 years, every ST tire I've had starts splitting and cracking.
I only run ST tires on my 12' trailer due to the size.
A D or E rated tire doesn't matter to me, I look at load ratings.
The E tires on my dually are rated to carry the same load as my last set of D rated tires. So, who knows why. I think the E's last a little longer and stay stiffer over time. I run 65 psi in both types, 80 psi makes the truck handle funny.
My toy hauler has the Tow Max 225 16" E's and so far so good. They have held up for two years.
I run them around 90 psi, side wall says 110 psi. I'll change them to LT tires when they wear out.
Those XPS tires are nice, too muck money for me though. My tires die of old age not tread wear. The Coopers, Dayton's and other imports all in LT work fine for me..... So far... .