This is a subject talked about constantly on RV forums.
The really good tires are Bridgestone Duravis R250 rib tires, Michelin XPS ribs (slightly more expensive) and the Goodyear G614's (very expensive.) The Sailun's are also good, but tire dealers selling them are few and far between.
Take all the rest of those Chinese tires and fill a landfill with them. They're of poor quality across the board--including the Goodyear Marathons.
The only ST tire that's okay is the Maxxis M8008's, but it's got a 65 mph speed limit. They come in all sizes for boats, utility trailers and RV's.
I paid $197 for Duravis R250's, and they're really, really thick and heavy duty. Costco was the cheapest place to buy them. Right now, Michelin has a $70 rebate on 4 tires, and again Costco is cheaper than TireRack, TreadDepot and Discount Tire Direct (online.)