As others have noted, your total weight, including everything you're carrying (which includes water-fresh, gray & black) should not exceed your GVWR, which is a tad under 10,000 lbs.
Many things, as already noted, can contribute to a tire failure.
Being overloaded is easier than you think. Go across a CAT Scale to find out.
Another big thing is speed. Find out the speed rating of your tires. Some trailer tires are rated above 65 (75), but most are 65. I see folks regularly running faster than their tires are rated for.
Low psi, but you have your TPMS, so that should not be an issue.
Sounds like none of your E tires have failed, so you may have found the solution.
Edited to add: Meant to include. On my previous trailer I ran OEM, Made in China, Castle Rock tires. Kept them at Max recommended PSI, trailer was always loaded within 200 lbs of the max GVWR, never exceeded the speed rating of 75 mph, and ran them for a bit over 20,000 miles without a single issue. Still had good tread when I sold the trailer earlier this summer.
I was concerned with everyone talking negative about "China Bombs", but my experience was not bad. The majority of my travel was in mid 80 to mid 90 degrees, and some in 100+ degrees. Additionally we traveled some really bad roads with a lot of very bad potholes. I was very impressed with how they held up.
On our new trailer we have the same China Brand tires. Less than 2,000 miles on them. We'll see how they hold up.