I have a 2006, 28' Puma. the loaded weight is aprx. 6800lbs. I thought it was a hitch issue, a lot of bouncing. Turns out it was my second thought, tires. Had hitch adjusted and ten miles down the tol...
It's advice, a suggestion, not mandatory to put on 16s or Es or 18s or 20. As far as load you can go to a scale and weigh axles and divide X 2 each axle by 2 and get the ammount of seight distributed over both sides. The DOT weighs trucks like this with a single scale and consider it close enough to be able to prove in court the weight on both sides. Load on both side at any given time on a road can differ.