I have made the decision to replace my GY Marathons (E)rated tires on my 15000 LB fiver. I am also replacing the wheels with 110PSI rated wheels. I'm leaning towards going with Sailun 637 235/80R/16. ...
I put on one Sailun G-rated at the end of 2013. The Sailun is all steel-belted, with a single sidewall belt. (The more expensive Michelin E-rated XPS Rib has two steel sidewall belts.)
I put 26,000 miles on the Sailun during 2014 and 2015. It shows little tread wear and no sign of sidewall cracking. I do keep tires covered when the unit is in storage.