Towing capacity is determined by the tow vehicle manufacturer, and the vehicle owner’s manual is the best source of information on towing capacity. You’ll also usually find this information on a sticker inside the vehicle door jamb, or on the manufacturer’s website. The Gross Combined Vehicle Weight (GCVW) is the most critical rating to determine. The GCVW is the maximum combined weight of the fully loaded tow vehicle with passengers, fuel and gear plus the weight of your boat (including its fuel and gear) and the trailer. The best way to accurately check GCVW is on a public scale at a truck stop or municipal facility. Weigh your rig with the fuel and gear you take to the water. Also pay attention to the maximum weight ratings of the trailer and the trailer hitch.