Whether you’re trailering equipment to a jobsite, hauling a camper for a weekend away or bringing horses out for a trail ride, towing enables countless projects and adventures. But what you can tow depends on the often-confounding concept of truck towing capacity. If you’re using a trailer, you’ll also need to factor in trailer capacity.

Figuring out how to interpret towing capacity can trigger flashbacks to math class. But you don’t need to remember calculus to get the answers you need. Here’s a primer to help with determining towing capacity for your vehicle and certain towing terms.

Understanding towing capacity: 5 key truck towing terms

Brush up on the meaning of these terms to understand how towing capacity — which in practice is more of a range than a single number — works.

1. Towing capacity: How much you can pull

The towing capacity is the maximum weight a vehicle can pull. Most truck manufacturers publish a towing capacity, which you can look up online. You can also calculate it yourself by subtracting the curb weight from the gross combination weight rating (both terms are defined below).

2. Curb weight: The weight of the truck or trailer

Curb weight is what your vehicle or trailer weighs with no passengers or cargo. On vehicles, you’ll find the curb weight listed on the driver’s door jam, near the tire pressure information. For trailers, curb weight, also known as trailer weight, is usually listed along with the other manufacturer specs.

3. GCWR: The maximum combined weight of truck and trailer

GCWR stands for gross combination weight rating. It’s the maximum amount your vehicle and attached trailer can weigh when fully loaded with cargo and passengers. Find the GCWR in the vehicle’s owner’s manual.

4. GVWR: The maximum weight a vehicle’s or trailer’s frame can carry

Both your truck and trailer have a GVWR, or gross vehicle weight rating. This is the maximum amount of weight the truck’s frame or trailer’s frame will support, including the weight of the truck or trailer itself (curb weight). For both safety and legal reasons, it’s important to stay at, or below, this number. For trucks, the GVWR is listed on a sticker on the driver’s side door jam. For trailers, it’s listed on the VIN sticker, usually located on the front left of the trailer frame.

5. Payload capacity: The maximum weight of cargo

Payload capacity is not the same as towing capacity. What is a payload capacity? It’s the maximum weight that can be loaded into your truck or trailer, including passengers. Subtract the curb weight from the GVWR to get the payload capacity.

How to interpret towing capacity: The three variables to keep in mind

Remember that the towing capacity stated in the manufacturer’s specifications is a maximum, not the amount you can tow under every condition. Actual towing capacity is determined by factors such as: your truck’s towing capacity, your trailer capacity and your tow hitch rating. It’s only as high as the lowest-rated component. If your truck has a towing capacity of 20,000 pounds but your trailer’s GVWR is 14,000 pounds, for example, you’ll need to stick with smaller loads.

Truck towing capacity

The engine, transmission and suspension all affect how much a truck can tow. Optional upgrades to the brakes, axels and radiator may help your truck tow larger loads. On the other hand, installing larger wheels or opting for low-resistance tires may decrease towing capacity.

Towing capacity chart for trucks

Here’s a rough, general guide to the towing capacity of pickup trucks of three common sizes. However, you'll want to understand the specifics of your truck and your job when deciding how much to tow.

Trailer capacity

A trailer that has a low curb weight but is designed for heavy loads will give you the most trailer payload capacity. A trailer with a braking system or independent suspension may help improve stop time, reduce trailer sway and give you better handling, while specialty trailers like a hydraulic ground level trailer or dump trailer can make challenging jobs easier.

Tow hitch rating

A tow hitch, also known as a trailer hitch, connects the vehicle and trailer. Hitches are grouped by class, with class 1 being the most lightweight and class 5 being the most heavy-duty. Hitches are rated for how much weight they can pull and the tongue weight, or downward pressure on the hitch, they can withstand.

If you’re using a class 4 or 5 tow hitch, which are appropriate for hauling large boats or multi-vehicle trailers, you may want to consider a weight distribution hitch, which can reduce strain on the bumper and improves handling.

Tips for towing safely

Adding weight and length to your vehicle can increase the risk of an accident. When you’re towing, remember these safety tips.

• Give yourself wiggle room. Never tow at the maximum capacity of your truck, trailer or tow hitch. Stick to 90% or less of the max capacity.

• Read the owner’s manual. The owner’s manual for the trailer may explain the best loading techniques and weight distribution for that trailer.

• Get properly licensed. If your load has a GVWR or GCWR greater than 26,000 pounds, you’ll need a commercial driver’s license (CDL).

• Consider safety upgrades. Extra-wide mirrors can reduce blind spots, and supplemental lighting on the trailer can make it more visible to other motorists.

Towing gets your cargo or equipment where you need it to be, whether that’s a jobsite or campsite. Understanding towing capacity will allow you to hitch up and hit the road without worry. You should consult with an expert regarding the specific circumstances, applicable rules and regulations related to your situation.

Visit our online marketplace to browse our selection of trucks and trailers for rent or stop in to your local United Rentals branch.