- Manufacturers determine the maximum weight capacity of a each hitch and stamp it with a class rating. Class one handles less weight than class five.
- Manufacturers determine the towing capacity (GTC) -- the maximum trailer weight the truck can haul -- of a truck and usually put the number in the manual or on their website.
- Each hitch can only handle a certain amount of weight pressing down vertically. Tongue weight equals 10 to 15 percent of the trailer weight.
- Add the weight of the trailer to the weight of the stuff within the trailer. For example, a horse trailer weighs 2,800 lbs and has two horses in it; the total gross trailer weight is 4,800 lbs. Average horses weigh 1,000 lbs. each. Multiply by 15 percent. This is the tongue weight, sometimes called hitch weight.