Actually fairly common for China made ST tires. You are not the first to post similar experience.
I recommend Goodyear Endurance or Carlisle Radial Trail HD
Both available in E rating
Or consider LT tires but you probably would need to go 16+ wheels.
Either way get tires rated for the full trailer GVWR as minimum.
So if by the manufactures numbers, GVWR 9699 lbs. plus Cargo 2731 lbs. totaling 12.430 lbs. can be safely towed.
BTW: GVWR is the max weight.
Actual scale weight deducted from GVWR is the remaining weight you can carry. Forget dry weight.