On anything other than a 22.5 tire, a trailer tire, at maximum air pressure should not exceed 65mph. And at that speed only for 2 hours.Tires should be allowed to cool down. A simple practice is to pull over every 2 hours( when driving constantly 60-65 mph) and pull out your hand help portable heat gun and check the tire temps. Gives you and idea what temp might be normal for your set up and may also indicate that a wheel bearing might be failing. Unless you have a tractor trailer, the 14, 15 and 16" tires we use are not built for high speed or the long haul.