The Sailun in question are ST trailer tires and has nothing to do with motorhome fitment.
Thanks Philly for the tip....
I use the Sailun S637 on my 16k GN triaxle stock trailer for several reasons . One being my and other family safety out on our hiways. The S637 ST have been around since the '10/'11 era mostly in the commercial service trailer industry and the last few years many have found out their a excellent tire for heavy rv trailers with 7k-8k axles.