I blew out 4 trailer tires in less than 6 months. The absolute best thing you can do, in my opinion, is to switch to a 16 inch rim, and get load range d or e tires for a light truck. I didn't want to spend the money on the rims. I bought 4 L/T 235/75/15 Uniroyal Liberators from wally world. About 80 bucks per tire. They were more than happy to mount them, and gave me a 50k mile warranty. I use my trailer for work, and probably pull it 10-12 thousand miles per year. I have had ZERO problems with these tires, and they have a nationwide replacement program, any wal mart, any where. The tire experts may argue, but when I looked up the D.O.T. qualifications for trailer tires, I learned alot. Like if it holds air and the manufacturer sais it's good, it's a trailer tire. They have such low standards that they cannot be mounted on a passenger vehicle. As a matter of fact, the Uniroyal's show zero wear still to this day. And they easily have 14k on them now. The one remaining trailer tire, (the spare) which was only one the ground for 600 miles, looks like it's on it's last leg. Your actual mileage may vary, no warranty expressed or implied.
For what it's worth, my trailer is a 2007 Timberlodge Sky 30. On the scales it is a little over 10k with the tanks and fridge empty. I yank it with an 02 7.3 excursion 4x4. If you see me at the campground, my favorite beer is Free, followed closely by cold.
Oh, and the trailer seems to track a lot better with these tires too, less wobble.