Know this might start a major debate but I am looking at replacing the OEM tires on my Bighorn 3260EL. It currently has TOW Max STR 235/80R-16 E rated tires and after just a year and only about 7000 m...
I see you are in KC. "Dob's tire" in Blue Springs installed Sailun S637's for me about 2 years ago. They were in a KC warehouse and they were delivered to the store the same day I bought them. Your rims will handle 110 PSI. It is stamped on the back side of the rim.
I also suggest you visit the "Heartland Owners forum". There is a lot of discussion about tires there.