Anyone that thinks a ST235/80R16E poly carcass ST tire off the rim has a stronger sidewall has never handled and compared it to a LT tire, particularly to a XPS Rib or R250 all steel carcass tire(which are the best two tires available for 5200 and 6K axles).
There is a lot of marketing hype surrounding ST tires that does not pan out in real life.
The new GY Endurance ST is to young to make final judgement on and Carlisle continues to tweak it's ST offering. The new Endurance is the only ST tire I would recommend at this point, which is based you GY commitment to making a good tire for trailer only use.