Supercab,
Have you tried Trailer Tires and Wheels - trailer tires, boat trailer tires, trailer wheels, boat trailer wheels, aluminum trailer wheels for sizing/wheels/tires? They are in NW Ohio and, while a small shop, he really knows what can fit in a size change.
Joe

 

after burning through 2 replacement..(plus the factory tires) in 4 years..gets darned expensive... i went to our local ford dealer.. ordered up the 4 cheapest 16 inch f rated light truck tires he could source... $112 cdn each.. brought him my old ones.. 2 at a time..lol.. and have NEVER BEEN HAPPIER.. almost 18k on them with NO ISSUES. we where averaging.. 17k out of the brand name trailer tires.. friggin things just don`t last.. We travel ALOT.. out every weekend (all year long) 30-60 days at a time.. or more during the summer.. due to the size and weight of our rig.. the rears scuff off twice as fast as the front tires... rotating helps drastically.. but...

 

I have had very good success with Maxxis brand ST tires made in Thailand. Many of us in the RV trailer world feel they are currently the best available. They will cost considerably more than the "Goodrides". Link to the Maxxis inflation and size chart; Trailer Tire Load/Inflation Chart | Maxxis USA

 

Everything is built to a price point, Chinese stuff is no different. The cheap ones are built cheap, and for the most part the expensive ones are built right.
When I was working on trucks, the company owner put Double Coin tires on all the trailers. The name was a hint that the tires were only rated at 55mph, at very high pressure, and rather low weight for a super single. They were the cheapest tires on the rack, though, but when you have a truck sitting out on the side of the road waiting for a tire, then down for a day while a new fender is put on, those cheap tires get expensive fast.