Our 5er (FR) has 16"LT tires and sidewall says 80 PSI cold and thats where they are set at 24/7/365. No problems. Coach weighs fully loaded, 13k and max GVW of 13,800.
As for the Sailun/God Year debate. GY are like 2x-3x more than Sailuns. Sailun while and "off brand" name has had very good results w/ RV tires. GY was only game in town for this size/rating---hence the higher price as they thought that had the market cornered. If Michelin made LT tires in "G" ratings, good bye GY & Sailun.