Here is some more scrub.
Attached is the MRT Sailun tire inflation chart. You may notice the S637T size is curiously absent. This chart applies to commercial tires (typically noted by the half sizes) which is what Sailun is known for.
Also attached the S637T specs sheet. It only notes 1 air pressure rating. 110 psi. This doesn't mean there isn't a load inflation chart for the S637T...just not on Sailuns website that I could find.
You can draw conclusions and apply commercial trucking procedures if you prefer I don't think it would hurt to run these tires a few pounds under the air pressure rating. Give it a try and make your own choices. Everything Tom is saying sounds right from a commercial trucking perspective. Others are quoting what RV manufacturers say, which also sounds right since they create "recreation" vehicles, which would not be good for sales if they told you it was a full time job to maintain them, rather than go with one pressure and enjoy the ride.