I got my 253RB two Saturday's ago. It was towed 1010 miles from the dealer to my house by a delivery company. Absolutely no sign of tire problems.
Like I have done with past trailers, I installed a Tire Pressure Monitoring System. TST is the manufacturer. I want to know tire pressure and temperature, especially on the 14" tires. My previous trailers were 15" so I was a little concerned about the reduced tire size.
I'll have to check the speed rating next time I'm near my trailer. It's in covered storage 6 miles away. I'm assuming the delivery company driver did not go 65 MPH for the 1010 miles it took to get to my house, although I will drive at the max speed for which the tires are rated, and conditions dictate. It's 102 degrees at my house today. If I were towing on the highway I'd monitor the tire temperature and maybe tow at less than rated tire speed.
I will replace the current tires with a set of Goodyear Endurance ST tires when current tires wear down.
I have read on other Forums discussions about ST versus LT tires on travel trailers. The bottom line is, LT tires are not designed to take the side loads that travel trailers or 5th wheels put on tires. ST tires are specifically designed to take the side loads. People can certainly install any type of tire they wish, however when it comes to safety, I spare no expense, and I believe what tire engineers are saying on various Forums.