Trailer sway

I'll add my 2 cents. You need new tires anyway, so going to a d would be good. Thats a heavy TT, max weight like 7000 lbs. Whats your truck rated to pull? Next i would air up my truck tires, and the ones on the TT. Also make sure you have more weight in the front of the TT wheels. So shift what you carry forward. See where your water tank is, might have to travel with it empty. Vut evwn woth tose things, you will feel it move when passed etc. Just the nature of towing something that big. Also i agree with the checking on a good sway bar.