Look for the Towmasters in the 13", 14" and 15" diameters...made by the same Chinese company that makes the Goodyear Marathon, but waaaay less expensive. Most Carlisle won't be domestically made either. I get these by the ocean container (1300 at a time) and I have had no failures.
In 16" sizes, you might as well go with LTs vs. STs. The Light Truck 10 plys (load range "e") are less prone to tread sep ( less nylon) than ST service trailer tires, and far more available.