Just saw this old post.  I too am looking to change tires on my new '18 F350 DRW.  I've had the Sailun S637 on our 5ver for 2 + years and 8000 miles.  Awesome tire, especially on a 13k 5ver.  Looking to upgrade the OEM Michelin tires LTX A/T.  Previously had great luck with the Toyo Open Country A/T 2 on my '03 GMC 2500HD Duramax.  Easily 50k+ miles, currently on second set.  Was planning on those for the new truck when I saw the Sailun Terramx A/T.  Simple Tire can get them to me for $100 less per tire than the Toyos.  Decisions....decisions!
Any update from those who chose the Sailun??
Thanks,
Happy 4th!!
Mike