Got 4 new 225/75/15's yesterday, switched from bias ply load stars to 8 ply radials. Seem to have smoothed out the trailer ride some, but they bulge some when loaded, which the others didn't do. I think they'll last longer, the others wore out after a year. Mainly from turning sharp and scrubbing on the road, I think. I ran over something Sunday afternoon that punched holes in both drivers side tires, so I just replaced them all. The main worry I've got is that when it's fully loaded, if I run over a curb when doing a U turn or something, which does happen sometimes, that I'll break a belt in the radials. Is that more likely with the radials than with the bias ply?

 

I have the same set up for tires(load range E) that you do trailer. It is a 26ft gooseneck and 260 JD Skidder, I take this trailer all over the farm, off road (lightly), thru town, and cross country, and I havn't had any problem with tires. Still pulls great I keep bearings greased and air in the tires.
Hope it helps. Just my experience.