I read through the forum and cannot find my exact issue, so I apologize if this question has come up elsewear. I recently got a 17' TT Forest River 17bhse, towing with a 2015 f150 with a class 3 hit...
Before you go getting crazy with $1,000 in new tires, make the simple changes first. 17' isn't a big trailer. Like others have said, get some weight forward. The trailer should be level or slightly nose down. I tow a 29', 8000 pound trailer with my F-150. As an experiment, fill your water tank full and tow it down the highway. See if there's a difference.