truck towing boat

Trailer Hitch Classes and Towing: What You Need to Know

Towing a trailer is not as easy as simply hitching it up to your vehicle and taking off. There are a number of factors that you’ll have to take into consideration before you’re ready to hitch a trailer up to your vehicle, and the information we’ve provided in this article will help you make the best selection when it comes to choosing the appropriate equipment to match your towing needs.

Before you can pick out a trailer hitch, however, you need to realize that the hitch alone will not give you the ability to tow – you’ll need some additional towing components, including a trailer ball and ball mount, wiring, and safety chains.

Here are some terms you’ll want to be familiar with in order to select the appropriate hitch for your towing needs.

Common terms

Gross Combination Weight Rating (GCWR)

Set forth by the tow vehicle’s manufacturer, this is the maximum weight limit allowed for towing for the combination of tow vehicle and trailer, including the weights of your cargo, safety equipment, passengers, and fuel.

You can find this information in your tow vehicle’s owner’s manual.

Gross Trailer Weight (GTW)

This is the actual weight of the fully loaded trailer, including the weight of all its cargo, fluids including fuel, and safety equipment such as straps, cargo nets, and wheel chocks.

The best way to determine GTW is by weighing your fully loaded trailer on a truck scale, but if that is not an option, you can add up the weights of the cargo, fluids, and safety equipment with the weight of the trailer itself (which you can find in the trailer’s owner’s manual). When in doubt, it is safest to round this figure up.

Hitch Class

Hitches are classified by their maximum weight capacity rating and receiver opening size. Classes range from I (lowest weight capacity and smallest opening size) to V (highest weight capacity and largest opening size), and each class has its own unique capacities and applications, which are explained below.

If you don’t know what class of hitch you have installed on your vehicle, you can check the label on the hitch or the owner’s manual.

Tongue Weight

This is the amount of the trailer’s weight that is exerted downward onto the hitch of the tow vehicle by the tongue of the trailer. In general, tongue weight should not be more than 10% of the GTW.

If you tow often, it may be beneficial to purchase a specialized scale to measure tongue weight. Many trailer dealers offer such scales. If you do not tow often, your trailer dealer may be willing to measure your tongue weight for you.

For trailers with a tongue weight of less than 300 lbs, you can measure the tongue weight with a common bathroom scale. You’ll need to set it up as it is in the diagram below.

Calculate tongue weight with bathroom scale

When using this setup to measure your trailer’s tongue weight, triple the number that the scale gives you. This will provide an accurate measurement.

Tongue Weight Capacity

This is the amount of weight that the tow vehicle can withstand exerted downward onto the hitch from the tongue of the trailer.

You can find this information in your tow vehicle’s owner’s manual.

Equipment

Towing Package

These are all the components that work together to connect the trailer and the tow vehicle, including the hitch, coupler, ball mount, trailer ball, and any necessary hitch adapters or extenders. It’s important to remember that the lowest rated towing component determines the maximum weight capacity that you can safely tow. Many vehicle manufacturers use the term Towing Package to refer to optional packages that include additional features such as suspension, cooling system, and software upgrades.

Hitch Adapter

Trailer hitch adapter

These fit into the receiver tube of your hitch and convert it from a 1-1/4" x 1-1/4" opening to a 2" x 2" opening, or vice versa. Keep in mind, using a trailer hitch adapter may reduce the overall capacity of your towing system.

Hitch Extender

Trailer hitch extender

These fit into the receiver tube of your hitch to extend it by several inches and create more clearance room for your tow vehicle’s bumper. Keep in mind, using a trailer hitch extender may reduce the overall capacity of your towing system.

Trailer Ball

Trailer hitch ball

This is the ball-shaped piece of equipment onto which the trailer coupler mounts and locks in place. These are attached to the ball mount, and come in a variety of sizes, including 1-7/8", 2", 2-5/16", and 3" (in some rare cases). These are also commonly referred to as hitch balls or coupler balls.

Coupler

Trailer hitch coupler

This is the front end of a trailer tongue that mounts and locks on top of the hitch ball. It is designed to swivel around the ball, allowing a trailer to make turns more easily.

Hitch Pin

Trailer hitch pin

This is the steel pin that locks the ball mount into the hitch tube.

Trailer Wiring

Trailer wiring harness

By law, trailer lights must be connected to your tow vehicle, and this requires trailer wiring harnesses. Typically, trailer connector wiring uses four to seven wires to control basic lighting and brake light functions.

Weight Distributing Hitch

This device is used to haul extremely heavy loads using a conventional hitch receiver. It distributes weight evenly between the rear and front wheels of the tow vehicle by attaching spring bars to the vehicle’s frame.

Sway Control

Think of a sway control as a brake pad or shock absorber that resists trailer and tongue sway (usually caused by wind gusts or passing vehicles) and keeps both the tow vehicle and trailer stable.

Trailer Hitch Classes and Applications

Hitches are classified by their maximum weight capacity rating and receiver opening size. Classes range from I (lowest weight capacity and smallest opening size) to V (highest weight capacity and largest opening size), and each class has its own unique capacities and applications.

Trailer hitch capacity chart

Class I

These light-duty hitch receivers are typically installed on passenger cars and smaller crossover SUVs. Class I hitches use a 1-1/4" x 1-1/4" receiver tube for the ball mount, and they are rated for towing a gross trailer weight of 2,000 lbs and a tongue weight of 200 lbs. These are usually used for towing light to moderate cargo including motorcycles, small utility trailers, and boats.

Opening Sizes GTW Tongue Weight Capacity
1-1/4" 2,000 lbs 200 lbs

Class II

These moderate-duty hitch receivers are typically installed on mid-sized sedans, small trucks, and minivans. Class II hitches use a 1-1/4" x 1-1/4" receiver tube for the ball mount, and they are rated for towing a gross trailer weight of 3,500 lbs and a tongue weight of 350 lbs. These are usually used for towing moderate cargo including include mid-sized boats, small campers, and snowmobiles.

Opening Sizes GTW Tongue Weight Capacity
1-1/4" 3,500 lbs 350 lbs
Trailer hitch opening size comparison

Class III

These versatile trailer hitch receivers are typically installed on pickup trucks, minivans, and full-size SUVs. Class III hitches use a 2" x 2" receiver tube for the ball mount, and they are rated for towing a gross trailer weight ranging from 3,500 to 6,000 lbs and a tongue weight ranging from 350 to 600 lbs. These are usually used for towing mid-sized campers, utility trailers, and mid-sized boats.

Opening Sizes GTW Tongue Weight Capacity
2" 3,500-6,000 lbs 350-600 lbs

Class IV

These heavy-duty hitch receivers are typically installed on heavy-duty pickup trucks and large SUVs. Class IV hitches use a 2" x 2" receiver tube for the ball mount, and they are rated for towing a gross trailer weight ranging from 6,000 to 10,000 lbs and a tongue weight ranging from 600 to 1,000 lbs. These are usually used for towing heavy loads, including large campers, boats, and toy haulers.

Opening Sizes GTW Tongue Weight Capacity
2" 6,000-10,000 lbs 600-1,000 lbs

Class V

These hitch receivers are the heaviest-duty models that can be installed on the rear of a tow vehicle, and they’re typically mounted on heavy-duty and commercial trucks. Class V hitches use a 2-1/2" x 2-1/2" receiver tube for the ball mount, and they are rated for towing a gross trailer weight of more than 10,000 lbs and a tongue weight ranging from 1,000 to 1,200 lbs. These are usually used for towing heavy loads including full-sized campers, large boats, and equipment trailers of all sizes.

Opening Sizes GTW Tongue Weight Capacity
2-1/2" Over 10,000 lbs 1,000-1,200 lbs

Fifth Wheel & Gooseneck

Gooseneck trailer

These less common hitches are designed for towing the heaviest recreational vehicles and working trailers, such as horse trailers. They provide a connection point in the bed of a 3/4-ton or 1-ton pickup truck, in front of the rear axle. Typically, fifth wheels are used for recreational vehicles, and goosenecks are used for working trailers.

Round vs Square Tube

Square and round tube trailer hitches side-by-side

In addition to choosing the correct class for your hitch, you’ll also want to determine whether you need a round or square tube hitch. Round tube hitches are usually selected for their sleek, streamlined design, however they also provide extra clearance between the bumpers, exhaust, and cross members attached to your tow vehicle’s frame. In some cases, but not all, a square tube hitch may have a slight structural advantage of 100 lbs tongue weight capacity and 1,000 lbs gross trailer weight capacity.

Find the hitch you need

In order to pick the right hitch, you’ll have to determine a few pieces of information.

  1. First, you will need to know the towing capacity of your tow vehicle. This information can be found in the vehicle’s owner’s manual.
  2. Next, determine the gross trailer weight of the trailer that you will be towing. This is the weight of the trailer when it is fully loaded with the cargo you intend to haul along with any safety equipment or extra supplies that will be in the trailer during transit.
  3. Now, you can use this handy CURT trailer hitch selector to make the right choice. All you need to do is plug in some information about your tow vehicle (year, make, model, vehicle) and it will take you to the correct set of hitches.
  4. The lowest-rated towing component determines the maximum weight capacity that you can safely tow. So, if you have a tow vehicle that can safely tow up to 10,000 lbs, but your hitch is only rated for 5,000 lbs, then that will drop the overall tow rating for your setup to 5,000 lbs. It’s always a good idea to purchase components with higher ratings than you think you will need.
  5. Once you’ve selected your hitch, it’s time to choose a ball mount that will fit your hitch and provide the right amount of drop or rise, if necessary, to make the trailer level.
  6. Finally, choose a trailer ball that will fit your trailer’s coupler.

Towing safety tips

Before you hit the road make sure you check:

  • the tire pressure on your tow vehicle and trailer and make any adjustments necessary.
  • the hitch, coupler, ball mount, safety chains, and other equipment (including hitch extenders and adapters if either is being used) that connect the trailer and the tow vehicle are properly secured and adjusted.
  • the wiring to make sure it is properly connected. It should not be touching the road, but it should be loose enough to make turns without disconnecting or damaging the wires.
  • all running lights, brake lights, turn signals, and hazard lights to make sure they are working properly.
  • the brakes on the tow vehicle and trailer (if equipped) to ensure that they are operating properly.
  • that all items are securely fastened on and in the trailer.
  • the trailer jack, tongue support, and any attached stabilizers to make sure they are raised and locked in place. Check load distribution to make sure the tow vehicle and trailer are properly balanced front-to-back and side-to-side.
  • the side- and rear-view mirrors to make sure you have good visibility.
  • your routes and restrictions on bridges and tunnels.
  • that you have packed wheel chocks and jack stands for when you reach your destination.

Hitch accessories

Hitch receivers are not just used for towing; they can also be used to mount a wide range of cargo carriers, bike racks, toy haulers, and more directly onto the rear of your vehicle.

Bike racks

Hitch-mounted bike rack

Designed to mount on the back of any vehicle equipped with a class II, III, or IV receiver hitch, our hitch bike racks come in a variety of styles to suit any need and hold up to five bicycles.

Cargo carriers

Hitch-mounted motorcycle carrier

Hitch-mounted cargo carriers are perfect when you need to haul a smaller load of cargo or simply don’t want to hook up a trailer. We offer a wide variety of hitch-mounted carriers designed specifically to help you safely transport a motorcycle, wheelchair, ATV, or load of cargo that work with class II, II, and IV hitches.

Hitch steps

Trailer hitch-mounted step

Easily reach the top of your vehicle’s roof to install a roof rack or load cargo into a roof box with these handy steps that mount directly into your vehicle’s class III or IV hitch receiver.

Other Helpful Resources

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