One theory is the ST tires sit for long periods and the UV gets them. Well I had 2 class C motor homes before I got 2 5th wheels and now I'm getting a small trailer.
Well my class C motor homes sat as much as my pull units, and sucked up just as much UV rays and over the life of both both class C units I never had a blow out. Of course these didn't have ST tires.
Then I got my 5th wheels with ST tires and blow outs became a way of life. I used E rated tires on the 16" wheels. All tires never exceeded 3 years of age. I used high pressure valves, tires were balanced, and pressure was always checked each day of travel. There was no uneven wear patterns, just good looking tires that went boom.
ST tires, Hmm.