Trailer Hitch Basics | Hitch Tongue Weight

There are a number of things to consider when determining whether a StowAway hitch cargo box or rack will work on your vehicle. The following outline will guide you through the trailer hitch basics to consider.

Trailer Hitch Receiver

Hitch Tongue Weight Capacity

One of the first things to consider when choosing a hitch carrier is the tongue weight capacity (TWC) of your vehicle. Tongue weight capacity refers to the maximum vertical weight that a vehicle's hitch can support under normal driving conditions.  Vehicles equipped with a factory installed hitch almost always specify the tongue weight capacity (TWC) for both your vehicle and your hitch, and they are generally the same. 

Trailer Hitch Tongue Weight

Vehicles equipped with a dealer installed or aftermarket hitch may have one TWC for the vehicle and another TWC for the hitch. In this case the lowest TWC is always the one to use when determining whether your vehicle can support a hitch carrier.   

Shorter, lighter vehicles tend to have a lower TWC while larger, heavier vehicles tend to a have a higher TWC. The best way to determine your vehicle's hitch Tongue Weight Capacity is to read your owner's manual. The owner's manual will provide detailed instructions and hitch tongue weight limitations, usually accompanied by tips for safe towing. Compare the owner's manual information with the certification plate on your driver's door sill. If your owner's manual does not provide tongue weight information call you local dealer to check with them.  

Sometimes you can only find information on the vehicle's or hitch's Gross Towing Capacity, sometimes referred to as (GTWR).  A quick way to calculate hitch Tongue Weight Capacity is to multiply your vehicle's Gross Towing Capacity (GTWR) by 10% (tongue weight = GTWR x 10%).  So, a vehicle and hitch with a 5000 lb towing weight capacity will have a tongue weight capacity of 500 lbs.  

Once you have identified your vehicle's TWC, subtract the weight of the carrier and frame to determine how much gear you can safely carry. For example, if you want to use a hitch bike rack and your vehicle has 1,500 lbs GTWR, then you have 150 lbs tongue capacity (1,500 x .10 = 150). If the weight of the bike rack is 40 lbs, you can carry bikes weighing up to a total of 110 lbs.   

Hitch Classes

Trailer hitches are commonly divided into five classes. Each class is based on the strength and size of the vehicle it is intended to be used on and the materials and design of the hitch itself.  Hitches range from Class I (Light Duty Hitches) to Class V (Extra Heavy-Duty Hitches). The most common factory-installed hitch sizes on SUVs, vans and RVs are Class III (Heavy Duty) and Class IV (Heavy Duty). Mid size SUVs commonly come equipped with Class II (Light - Medium Duty) hitches. Sedans and smaller vehicles are generally rated for Class 1 hitches or not rated for a hitch at all.  These vehicles are not suitable for a Stowaway hitch cargo carrier. 

The following trailer hitch basics chart shows the hitch Tongue Weight Capacities that different hitch classes are designed to support.

Check your owner's manual or contact your dealer to confirm your factory-installed hitch’s class of trailer hitch ratings. If you're considering installing an aftermarket trailer hitch, please see the Installing a Hitch on Your Vehicle section below for more information.

Hitch Class Tongue Weight Capacity* Towing Capacity*
Class I 100 - 150 lbs 1,000 - 1,500 lbs
Class II 200-350 lbs 2,000 - 3,500 lbs
Class III 350-500 lbs 7,500 lbs
Class IV 500+ lbs 10,000 lbs

*Approximation: Depends upon vehicle.

Hitch Sizes

Hitches are sometimes identified by size rather than class. Hitch sizes refer to the inside dimension of a vehicle's hitch receiver (measure one side).  Class III and Class IV hitches have a measurement of 2 inches, thus they are often referred to as "2 inch receivers." Class I and some Class II hitches generally have a measurement of 1.25 inches, thus they are often referred to as "1.25 inch receivers."  Class V hitches have an inside measurement of 2.5" and are designed for heavier loads.  

Note: Some manufacturers fabricate Class I and II hitches with a 2 inch hitch opening to accommodate a greater range of hitch accessories, so do not assume that a 2 inch opening equates to a Class III or Class IV receiver hitch.

2" hitches almost always have greater hitch Tongue Weight Capacities than 1.25" hitch receivers.  Check your owner's manual, contact your dealer, or simply measure your receiver opening's diameter to determine your hitch size.

StowAway Hitch Carrier Compatibility

Every StowAway Cargo Carrier and Rack slides directly into the hitch receiver that is mounted to your vehicle. StowAway carriers are designed for use with Class II (1.25 inch), III (2 inch) and IV (2 inch) hitches. 

Refer to the trailer hitch basics chart below to see if your hitch receiver is compatible with one of our StowAway cargo carriers.

StowAway Products Class II (1.25") Class III (2") Class IV (2")
MAX Cargo Carrier X X
Standard Cargo Carrier X X X
Hitch Cargo Racks X X X

StowAway Cargo Boxes designed for 2" hitches can carry up to 200 lbs of gear.  Those designed for Class II 1.25" hitches can carry up to 125 lbs of gear. 

Hitch Converters

Hitch Converters are hitch accessory products designed to change the size of your hitch receiver opening. The most common Hitch Converter used with SUVs, vans, and RVs is the 1.25 to 2 inch converter, which essentially convert a 1.25" hitch opening into a 2" hitch opening. 

Note: Using a Hitch Converter does not change the hitch's class rating or Tongue Weight Capacity, it only changes the size of the receiver opening. For this reason, we do not recommend using a 1.25 to 2 inch Hitch Converter with any of our StowAway Cargo Carriers. Attempting to use such a converter with one of our carriers could place undue stress on your vehicle's frame and/or hitch.

Hitch Extenders

Hitch Extenders are a hitch accessory that increases the distance between the back end of your vehicle and the hitch receiver opening. They are often used to accommodate rear-mounted spare tires and ladders, or to increase the turning clearance of a towed vehicle.

Due to the weight of our StowAway Cargo Carriers and cargo racks, we only recommend using a Hitch Extender on a Class 3 or above (2 inch) hitch. We also recommend the use of a Hitch Tightener to secure the junction between the Hitch Extender and the hitch, as well as the carrier's frame and the Hitch Extender. The Hitch Tighteners will tighten the connections of the Hitch Extender and help to prevent hitch wobble.  

Note: We do not recommend using a Hitch Extender on a 1.25 inch trailer hitch, or a Hitch Extender longer than 7 inches (measure from hitch pin hole to hitch pin hole on the Extender).

Also note that the use of a Hitch Extender in conjunction with a StowAway Cargo Carrier decreases the carrying capacity of the StowAway by 1/3. Therefore, you should limit the weight of your gear to roughly 130 lbs when you use your StowAway Cargo Carrier with a Hitch Extender.

Installing a Hitch on Your Vehicle

If you intend to purchase an aftermarket trailer hitch, be sure to take into account your vehicle's Tongue Weight Capacity (TWC). It is not uncommon to find an aftermarket hitch rated for 300 lbs TWC for installation on a vehicle rated for only 150 lbs TWC.  Remember that your TWC for a hitch carrier is the lowest of the hitch and vehicle ratings.   

A common misconception is that by placing a Class III or IV (2 inch) hitch on a lighter-duty vehicle, the vehicle will be able to support the TWC that these heavier-duty hitches are designed to support. This is an incorrect assumption that could very easily place undue stress on your vehicle's frame and/or hitch if you were to max out your hitch's TWC. Your vehicle's TWC will not increase when you install a hitch, even if the hitch is designed to support a weight greater than your vehicle's max tongue weight capacity.

The following chart contains some rough guidelines to follow when purchasing an aftermarket trailer hitch.

Vehicle TWC Recommended Hitch Class*
200-300 lbs Class II (1.25" Hitch)
300-500 lbs Class III or IV (2" Hitch)
Over 500 lbs Class IV (2" Hitch)

*Approximation: Depends upon your vehicle.

Additional Questions?

For additional questions or concerns on trailer hitch basics, feel free to contact one of our cargo carrier specialists via email or phone, toll-free at 800-943-5377.