I had to replace a couple of tires this year that just started coming apart. Guy said it was dry rotting, happened a lot after the really dry summer we had two yrs ago, he says.
I have had extraordinarily bad luck with trailer tires. I think I have four different brands on there now. I still use the stock 215/75/14 inch tire size. The two I can see right now are a BCT and a Karrier, both C load rated at 1870lbs.
I have had problems with the tires rubbing on the inside on the fender board. Eventually, they fail. I run 1/4" spacers on each tire now. You must tighten and retighten a couple of times with spacers, but they have helped my tire reliability.
While searching for tires of that size, I found this Airstream trailer forum in which guys discuss how their stock Marathons (same size) come apart when they drive on dirt roads or uneven concrete, or are maneuvered a lot. A couple of them recommend switching to 15" wheels and tires. Here's the link, pretty interesting.
http://www.airforums.com/forums/f465/14-215-75-to-15-225-75-wheel-and-tire-upgrade-40248.html