I've had good luck with ST tires on relatively light weight trailers. We got seven years out of our last set of Goodyear Marathons before I noticed a bulge in the tread. 3-5 years is good for any tires including LT tires in my experience. The only trailer that seemed to have problems with ST tires was our 10,400 lb actual weight Jayco Eagle 5th wheel. It had 225/75 R15 D's. I was lucky to get two years out of a set. I'd keep your ST's aired to the max on the sidewalls and like with any tire on any vehicle, check for anything unusual and check them often.