Trailer tires are not built with the same safety specifications that vehicle tires are held to... Many folks relate experiences of blow outs and other catastrophic failures. These can be serious and life threatening at high speeds. The cause is usually age related combined with overheating. Tires overheat with weight and speed. Age weakens the sidewall and you may see cracking or dry rot. I replace my trailer tires every 5 years because of this. Trailer tires never see the miles that your car tires earn so age becomes a good guide for replacement. When buying tires, spend a little more money and get a higher weight rated tire, radials are always better too. A lot of lower weight tires have speed limits lower than highway speeds. Pay attention to the speed rating too. These factors together are why so may experience blow outs. They have a tire that is over its speed limit at highway speeds; they overload it for their trailer; and it's aging. These create enough heat that it blows out. Related to aging is the sun's UV damage. This is why it's recommended to have covers for your tires to protect them from the sun's UV damage. Lastly, check your pressure before use. Ignored for too long while sitting usually creates a serious under inflation pressure, making the heat build up more rapidly. When you put air in them, put the pressure in a cold tire that's on the sidewall. Car tires have a range but trailer tire do not... Following these guidelines will keep you from having a tire failure. I've never had a blown tire on a trailer in 40 years of towing.