How Do You Calculate Towing Capacity? 9 Terms You Need To Know

If you are looking for an SUV to haul your toys like a motorcycle or camper, or you need to know if your full-size truck can handle moving around some farming equipment like a tractor or horse trailer, chances are you’ve been looking to figure out the towing capacity necessary to get the job done. 

Towing Capacity

Whenever you are looking into pulling or hauling a load with your truck or SUV you are going to be running into this term: towing capacity. So, what is towing capacity? Well, simply put the towing capacity is a number. It’s the amount of weight your vehicle is rated to pull safely.

It’s not all quite as straightforward as that, though. While vehicle manufacturers will often declare a figure which is meant to represent the towing capacity, it’s not so cut and dry. 

The towing capacity can change depending on what towing configuration you are using and how the weight is distributed. Motorists will need to keep a factor in not just the posted weight of the trailer but also any additional passengers and associated cargo.

While configuring a tow load properly is not as simple as some straight-up addition, it’s essential for the safety of the tow vehicle and its passengers.

A small SUV with a ball hitch has a low towing capacity.

Towing Capacity Glossary

No discussion of towing capacity would be complete without a list of terms that drivers are likely to come across when attempting to calculate what they can safely tow. Many of these terms may look complicated with their many abbreviations, but this list should serve as an easy reference.

Braked vs. Unbraked Towing Capacity

The towing capacity can be wildly different depending on whether or not the trailer that is being towed has its own brake system. A trailer that has brakes will communicate with the tow vehicle so that both systems will work in tandem, being controlled by the same brake pedal inside the tow vehicle. If a vehicle is towing a trailer that has its own brakes, this can greatly increase the total towing capacity. 

Curb Weight

Curb weight refers to the gross weight of a vehicle, including a full tank of gas, but with no passengers or cargo. 

Dry Weight

Dry weight refers to the gross weight of a vehicle, without gasoline, motor oil, or any other fluids. Often, this metric will not be included in any calculations of towing capacity.

GAWR

This stands for Gross Axle Weight Rating. It represents the maximum weight that a single axle can support. Usually, the front and rear axles will have a different GAWR due to different materials, diameters, or unequal weight distribution of the vehicle itself.

GCVWR

The maximum acceptable weight of your vehicle and trailer including the weight of all passengers and cargo is referred to as the Gross Combined Vehicle Weight Rating. Each tow vehicle and trailer will have its own individual GVWR which can be combined to find the GCVWR.

GTW

The complete weight of a trailer, fully loaded with all cargo, is referred to as the Gross Trailer Weight. Imagine if you could bring your fully loaded trailer inside and place it on your bathroom scale. The reading given by the scale would be the GTW.

Knowing your Gross Trailer Weight is critical to safe towing. Attempting to tow a vehicle with a GTW that is higher than your tow vehicle’s towing capacity could result in damages to the tow vehicle or the trailer. Worse, if the GTW is beyond the recommended towing capacity it could cause you to lose control of the vehicle resulting in an accident. 

Remember: The Gross Trailer Weight is the total weight of the trailer AND all associated cargo.

GVWR

The maximum amount of weight a vehicle can hold at rest, including passengers and cargo, is called the Gross Vehicle Weight Rating. This rating takes into account an individual vehicle’s suspension, tires, axles, and frame strength.

This is separate from the towing capacity. The GVWR refers to the load a vehicle can support vertically, while the towing capacity refers to the amount of weight your vehicle can pull.

Payload

The payload is the maximum total weight of possible cargo. You can find the max payload weight by subtracting the curb weight from the GVWR.

Tongue Weight

The tongue weight (TW) refers to the downward force being applied to the trailer hitch by the tongue of the trailer. This figure can change depending on load distribution within the trailer.

How Can I Determine My Towing Capacity?

In order to calculate your vehicle’s total towing capacity, you’ll need to pull together a few figures. 

First, you’ll need to know the GCVWR – that’s the maximum allowed weight of the tow vehicle and trailer combined, including all cargo and passengers. Don’t forget to include the items you keep in your car at all times as well as the ones you plan to load up for the specific trip.

Once you know the GCVWR, you’ll want to subtract the curb weight. This will leave you with a figure that should absolutely never be exceeded, according to the manufacturer’s specifications. To account for human error, it’s recommended that you actually never come to within 10% of this figure when making your calculations.

A simplified formula for determining safe towing capacity might look like this: 

Towing capacity = 0.9(GCVWR – Curb weight)

Drivers should aim to make their calculations very carefully. Accounting for all cargo and provisions in this process is incredibly important in this process as mistakes could lead to serious consequences.

In the end, calculating your towing capacity doesn’t need to be as stressful as some people make it out to be. As long as you stick to all of the manufacturer’s specifications and make your calculations studiously, all should be well.

As always, if you need towing in or around Spokane, you can skip all the math and call Jimmy’s Spokane Towing to have the job handled by professionals.