Wow, another trailer tire thread. I will throw in my $.02 worth.
Tire quality, overloading and incorrect pressure are the big three. Throw in age and you probably have covered the main issues surrounding tires failing.
I purchased a new hybrid a few years back which had been sitting on the lot for over a year. I got it in the fall and by the next spring the tires were at least two years old. No mileage, but two years of age. They were also of questionable quality based on all the posts I read on this forum.
To make a long story short, one blew on me even though I watched them carefully, had them aired up to the sidewall max, and even checked them at every stop. It was 72 outside and one blew about 15 minutes after we had stopped for a break. What I found out was that Starcraft had put these load range C tires on because they covered more than the trailer's GVW but only something like 200 pounds more!
I purchased an Airstream about 4 years ago and it had very few miles on it with the original Goodyear Marathons. This trailer sat in the hot sun for a long time. After one year, I replaced all of the tires with Maxxis, LRD and now I have a very nice cushion for weight. The Marathons were showing signs of tread separation and they were an American company! Wait, an American company who moved their production to China and chose not to do the job of quality control that they should. I agree with the earlier comments. It isn't the country where the tires are made, it is the company who simply wants to cut corners and make an extra buck.
Maxxis are not made in the USA but they do have a very good quality control system and their tires are very good, at least when compared to everything else.
So, get new tires. Get a good brand or at least a tire that a reputable dealer will stand behind, get it large enough to carry the weight and then get one a bit bigger, bigger in the sense of load rating. If you have lots of money, get new wheels and buy some LT tires. Some trailers can not accommodate the larger wheels so be careful. Air them up to the max, drive at or below 65 and check them frequently. This is your best insurance against major heartache.
Good luck.
