A tow hitch is a vehicle-mounted coupling device that creates the secure connection point between your vehicle and a trailer or other towable load.
Whether you are hauling a boat, a cargo carrier, or a bike rack, the hitch is the hardware that makes it possible. The term is often used interchangeably with “trailer hitch,” and in most cases it refers to a receiver-style hitch—a square tube welded to your vehicle’s frame that accepts a removable ball mount. That receiver tube is the part that determines which accessories will fit your vehicle, so knowing its size is the first step in any towing setup.
What A Tow Hitch Does And How It Works
A hitch provides a solid, engineered attachment point for anything you need to pull or carry behind your vehicle. The complete towing setup involves several parts: the receiver on the vehicle, a ball mount that slides into it, a trailer ball sized to match your trailer’s coupler, and safety chains as a backup connection. Trailer wiring may also be part of the package, letting the vehicle’s brake and turn signals control the trailer’s lights.
U-Haul’s glossary defines a trailer hitch as a device that attaches directly to the tow vehicle and provides the connection between the vehicle and the trailer. CURT’s glossary adds that “tow hitch” is another name for a trailer hitch, usually meaning a receiver hitch with a tube that accepts a shank, though the term can also apply to 5th wheel or gooseneck hitches used by larger trucks. The core job is always the same: a secure, rated connection that keeps your load attached on the road.
Hitch Classes And Receiver Sizes Explained
Hitches in the US market are grouped into classes based on their weight capacity, and the receiver opening size generally rises with the class. The table below shows the commonly published ranges, but treat these as starting points—the exact rating printed on your specific hitch and in your vehicle’s owner’s manual is the number that matters.
The receiver opening is what determines which ball mount or accessory fits, so measure it before buying anything.
| Hitch Class | Typical Receiver Size | Common GTW Rating |
|---|---|---|
| Class I | 1.25 in | Up to 2,000 lbs |
| Class II | 1.25 in | Up to 3,500 lbs |
| Class III | 2 in | 5,000–8,000 lbs |
| Class IV | 2 in | 7,500–12,000 lbs |
| Class V | 2.5 in | 12,000–20,000 lbs |
Class ratings vary by manufacturer, so the label on the hitch itself is the final authority. Many heavier-duty hitches also carry a separate weight-distribution rating, which is often higher than the weight-carrying figure. If you are shopping for a van hitch, our tested roundup of the best van tow hitches covers the top options for full-size vans and campers.
GTW vs. Tongue Weight: Two Numbers That Matter
Understanding the two weight limits on a hitch prevents most mistakes. Gross Trailer Weight (GTW) is the total weight of the trailer and everything in it, while tongue weight is the downward force the trailer’s coupler presses onto the ball. They are separate limits—a trailer can be under the GTW limit while its tongue weight still exceeds the hitch’s rating.
CURT’s hitch-selection guidance identifies GTW, tongue weight, and receiver opening size as the three key variables for choosing the right setup. Matching the ball mount’s shank size to the receiver is just as critical—a 2-inch shank will not seat in a 1.25-inch receiver, and forcing it is a compatibility failure waiting to happen.
Common Mistakes And How To Avoid Them
Most hitch problems come down to a few recurring mistakes. Knowing them upfront keeps your setup legal and safe.
- Confusing the parts — the tow hitch is the receiver on the vehicle; the ball mount and ball are separate removable pieces.
- Trusting class numbers alone — always verify the rated capacity printed on the specific hitch and in your vehicle’s manual, since class ranges overlap.
- Mismatching the receiver size — the shank must fit the receiver tube exactly;
- Overlooking tongue weight — exceeding this limit strains the rear suspension and can destabilize the vehicle.
- Assuming universality — a hitch rated for one vehicle is not automatically safe for another, and accessories sized for one receiver may not fit yours.
Safety chains should always be properly crossed and secured, and trailer wiring must be functional so your brake lights and signals work on the trailer. When in doubt, the owner’s manual for both the vehicle and the hitch is the reference that overrides any generic chart.
References & Sources
- Kelley Blue Book. “What Is a Tow Hitch?” Explains the term, common components, and typical use cases.
- CURT Manufacturing. “Basic Towing Components & Hitch Guide.” Defines tow hitch terminology and the key selection variables of GTW, tongue weight, and receiver size.
- U-Haul. “Trailer Hitch Glossary.” Provides the standard definition of a trailer hitch as the connection device between vehicle and trailer.