Our trailer has been sitting for 2 years. I was checking the psi and only down about 5 pounds. Both tires on the passenger side have cracks in the sidewall and these have had tire covers on the whole...
The Carlisle Radial Trail HD has a good rep and one of the top three ST tire mfg I would recommend. Others I would recommend mostly on reviews....actual use from rv and non rv trailer users.....other trailering websites are the Provider from Taskmaster and the Goodyear Endurance.