What's Your Recommendation for Tires?

Your trailer is just as heavy as mine. I'd stick with the "LT" tires as they can handle the load. Yes the "ST" tire's sidewalls can flex better in backing conditions, IMO, they do not stand up to the heavy weight and heat during the summer. When you purchase new tires, before you pay, check the date code on the tires as they may have already been sitting around for a year. (rule of thumb, after 5 years of use, you're on borrowed time with any trailer tire, great tread or not) I've had zero problems with the General Ameritrac's and Goodyear Wrangler LT's.