Take Cargo carrying capacity (CCC) from yellow driver C pillar sticker, subtract driver and passenger weights, any added accessory weight, random stuff weight, anything in the bed and your leftover CCC will dictate max tongue weight, which is not to exceed 1100lbs for a weight distribution hitch or 500lbs for a standard hitch.
For most travel trailers tongue weight will be 12-13% of loaded weight of trailer, any flat deck will vary from 10-15% depending on load placement.
The Vin lookup on ramtrucks.com will give you both payload and the fictional max trailer weight, which can’t be achieved without ignoring physics. Realistically most moderately optioned (excluding Laramie, longhorn and limited) ram 1500’s can safely tow a trailer in the 8500lb max loaded weight range. Comfortably theses trucks max out around the 7500-8000lb range. For the well optioned trucks, Laramie, longhorn, limited or a highly optioned rebel the CCC is likely low 1300lbs or as far down as high 900lbs so towing should max at about 6500lbs.