Can you buy a non-China bomb tire for a trailer?

Either Goodyear Endurance or Maxxis tires will serve you well and are not China bombs.

Nothing wrong with P rated tires on a trailer.

I had good year marathons on my 2003 trailers. 13" They were original and over 10 years old before I replaced them.. Bought the trailer that way. They looked new with no dry rot. I did one season and replaced after a valve stem leaked.

I believe they are 75mph rated.

https://www.discounttiredirect.com/buy-tires/goodyear-marathon/p/30556

The 13" part is likely your weak point. If you changed to 14", you could get Goodyear Endurance. If you could go all the way up to 15", you would have a lot of options in an LT.

I know people beat on Chinese tires regularly, but I have had Marathon's that were made in both the USA and Canada blow out just like everything else. That said, I put Endurance on my boat trailer, and it handles significantly better than with the non-name brand that were on as OEM.

I am wary of using them on a multi-axle trailer due to the forces on the sidewalls, but on a single axle you really only need to worry about sufficient weight capacity and choosing a tread that will track well.

If the bolt pattern is a common size and you have sufficient fender clearance, you might think about going up in tire diameter and capacity in one of the stock trailer wheel sizes.

My enclosed trailer used four LRD 15" tires and when they wore out I went with the same size LRE to give me better wear and puncture resistance. If I didn't find these ST tires, I was going to use a taller tire with more capacity but had to be careful to go too tall and rub when under load.

It is a single axle trailer, but I thought you aren't supposed to put passenger tires on a trailer?

I think Maxxis trailer tires are made in Thailand so maybe I will just have to use Maxxis.

Can you find P-rated tires in that size with sufficient weight rating? I'm assuming this is a single axle trailer that does not have tire scrub in turns.