I am still of the opinion most tire issues are caused by:
Age
Sitting Still Long Periods
Under inflation
Overloaded
Over speed
Road hazards
You put all of these together either in total or in part and you have potential for tire damage and failure. Some of us are very good at eliminating some of these issues, none of us are able to eliminate all of them. Tires are going to fail at times. An earlier post referred to why we all carry spares.
I have run ST tires on various trailer for many years with very few problems. Most every flat/blowout I have had was on the right rear tire. I'm sure this is because the right front trailer tire runs over something, kicks it up a bit and the rear tire gets it. Did I get a bit too close to the edge of the road? Probably so.
With all of this being said, I did upgrade my original E rated tires to G's a couple of months ago. Not because I was scared of the original ST E tires, but because of the tire loading and tire age. I have 3,000 lbs load per tire and the extra capacity of the G rated tires just made me feel better (Yes I weighed my loaded 5'er). Were my original E rated tires worn out? Absolutely not, but they were a tad over 4 years old and I won't run them longer than that. JMHO