There is a very large marketing campaign around the cheap ST tires. If you have 16" 6 hole wheels, you most likely have 5200 or 6K axles. There are many LT235/85R16E or LT245/7516E tires that will only out live ST235/80R16E's by a factor of 2 or 3 times.
Three best in order.
Michelin XPS Rib (All Steel)
Bridgestone Duravis R250 (All Steel)
Bridgestone Duravis R500HD (Two ply poly sidewall)
Depending of weight there are many other LT's that might work fine, however you did not provide any details on our trailer and/or type of use that is planned. Want to see America, then the three above should be on your list.
Chris