Just went through a destructive blow out on a Sailun 235/85R16 tire on my Fuzion 357 toy hauler. I have less than 2500 miles on the tires, never been stored outside good tread and had the correct tire pressure in them when we left for our last adventure......and the tire blew 2 miles down the road, complete sidewall blowout.
After a lot of research, I found out there are as many opinions about tire brands as there are tire manufacturers out there.
All brands experience premature failures from time to time. Some of them with no explanation.
Many will tell you do not buy "China bombs", tires manufactured in China....like your Sailuns. Guess what, very few trailer tires are manufactured in the good old USA. Goodyear being one of them but they have a slightly lower load rating than your G rated Sailun tires.
The following is what my research led me to believe are important factors for our trailer tires.......again just my opinion:
Invest in a good TPMS to monitor your tires as you drive.
Make sure you have tires rated properly for your camper's load
Seriously think about replacing your trailer tires after 3 years regardless of appearance.
Keep the tire pressure where it needs to be for your load...lower pressure = a lower load rating.
Watch for dry rotting and minimize extended storage outside without tire covers.
Do not exceed the speed rating of your tires while trailering.
If your tires are within these parameters, I would cross my fingers and roll on down the road until you are outside one of these recommended parameters. I would then seriously consider replacing them. Yes, it sounds premature and expensive to replace tires that appear to be in "good" shape visually. That being said, I'll bet you it is less expensive than the damage done to my camper with this latest blow out.