Even before the towing equipment, it’s important that the tow vehicle has the proper capacity. Contact your car dealer or the vehicle manufacturer to determine the specifications for your vehicle. You’ll want those specifications to meet, or even better, exceed your requirements.
The following definitions should help in understanding your vehicle’s specifications.
- Gross Combination Weight Rating (gcwr): The total allowable weight of the truck, the trailer, the cargo in each, fluids and occupants.
- Gross Vehicle Weight Rating (gvwr): The total allowable weight for the vehicle, including fluids, options, occupants, hitch, cargo, and trailer hitch weight. The trailer’s gvwr, sometimes referred to as Gross Trailer Weight Rating, is the total allowable weight of the trailer, fluids, occupants, options and cargo.
- Gross Axle Weight Rating (gawr): The total allowable weight on any given individual axle. Note that this includes the weight of the tires, wheels, brakes, and axle itself.
- Maximum Tow Rating: The manufacturer’s weight limit for towed loads. For conventional trailers, this normally includes a hitch-weight limit as well; for fifth-wheels, the pin weight is applied to the truck’s gvwr and its rear-axle gawr.1
It’s also important to refer to your vehicle’s operators manual prior to purchasing a towing system. Often your owner’s manual will have important information regarding your vehicle’s capabilities and limitations.
To choose the appropriate tow system, you’ll need to know your trailer’s specifications.
- Gross Trailer Weight (GTW) The Gross Trailer Weight is the weight of the trailer and cargo. This can be either computed using the trailer manufacturer’s weight specifications (curb or “dry” weight) added to your cargo weight, or by having the fully loaded trailer weighed on a vehicle scale.
- Tongue Weight – Tongue weight is the downward force that is exerted on the hitch ball by the coupler. The tongue weight will vary depending on where the load is positioned in relationship to the trailer’s axle(s).
- Trailer Coupler and Size
For most general towing, the trailer coupler will accept a hitch ball. Hitch balls can be sized 1-7/8”, 2” and 2-5/16” and the necessary size is normally stamped on the trailer coupler. Hitch balls carry a weight rating and their capacity increases as their size and shank diameter increases.Some heavy duty and off road trailers will have a pintle eye for the trailer’s connection to the tow vehicle. These trailers require a pintle hook be used on the tow vehicle. Pintle hooks are manufactured with various ratings and configurations.Other heavy duty trailer configurations may have a goose neck or fifth wheel connection. Gooseneck and fifth wheel receiver hitches are heavy-duty towing applications with weight ratings from 15K to 30K lbs.
The three most common types of hitches are the receiver, gooseneck, and fifth wheel hitch. The receiver hitch is typically attached to the frame at the rear of the vehicle. The receiver hitch will have a 1-1/4” or 2” square opening which accepts a ball mount. The ball mount has the hitch ball attached and is held in the receiver by a pin.
There are five different classes of receiver hitches and they range from Class 1 to Class 5. Class 1 and Class 2 receivers have a 1-1/4” square opening; most Class 3 to Class 5 hitches will have a 2” opening. Hitch manufacturers will normally produce a hitch that best matches the weight capacity of the specific vehicle. They do not produce a hitch in each class for every vehicle. The gross trailer weight capacity of the receiver hitch increases from a Class 1 to Class 5 with each hitch having its own specific rating.
What can cause some confusion is that most Class 3 to Class 5 hitches carry two ratings. One is the weight carrying rating; the other is the weight distribution rating. The first is when a ball mount is used in the receiver; the second is when weight distribution is used. To achieve the greater of the two hitch receiver weight ratings, weight distribution will need to be used.
Weight distribution achieves a greater weight rating by using a heavy-duty, adjustable hitch head with either round or trunnion style bars that attach to the tongue of the trailer. The weight distribution system allows the load to be more evenly distributed on the trailer wheels and tow vehicle. This even distribution allows for a more stable ride and better control for braking and steering.
Gooseneck and Fifth Wheel Hitches
Gooseneck and fifth wheel hitches mount in and through a truck bed, and offer an increased gross trailer weight towing capacity. In addition to a greater capacity, these hitch types also offer improved maneuverability of the trailer. Gooseneck and fifth wheel hitch models vary based on their weight capacities, ease-of-use, and ability to be removed.
The purpose of a sway control unit is to reduce the lateral movements of the trailer caused by the wind. Sway control can be added to a weight distribution system to help the trailer track in a straight line. Most sway controls work by friction and have a lever release to restore turning ability at
The use of an electronic trailer brake control improves handling and safety, lessens wear on the tow vehicle, and is often required by law. In Illinois, an electronic brake control is required for most trailers with a gross vehicle weight rating of over 3000 lbs.
The two most common types of brake control systems are timed and proportional. Timed systems measure the length of time the brake pedal is depressed, and after a specified period of time, the timed unit applies 100% braking power. The timed system does not determine the deceleration of the tow vehicle; it applies braking only based on how long the pedal is pressed.
Proportional based controls use a sensing device, determine the tow vehicle’s deceleration, and then apply the trailer brakes to match. Proportional controls deliver power to the trailer brakes in direct relationship to the actual physical deceleration of the tow vehicle. Proportional braking is preferred as it offers a quicker response, appropriate braking, and helps prevent glazing of the trailer brakes.