I think many things contribute to trailer tire failure. There will always be that nail or some sort of debris that is unavoidable and by the time you get off the road whatever it was is long gone. Many tires are flat out overloaded, either by the manufac new or by all our stuff we throw in the camper. Many don't keep the air correct in their tires and just assume if they were checked the last time out they will be ok this trip. Another big one is your trailer not being level, too much weight on either the front or rear tires. Going too fast whether your tires can take it or not, they build up lots of heat and sometimes just can't take it. Also any of the above said mixed with speed can have bad results. Lastly, some tires are just plain JUNK!
Remember to air the spare!