GMC's new heavy duty truck can tow 22,500 pounds

It's been put through several "extreme tests," including a climatic wind tunnel.

By Kristin Shaw | Published Aug 14, 2023 6:00 PM EDT

If you have never towed a trailer, camper, or boat before, it may seem daunting. With the towed vehicle attached, the SUV or truck doing the driving feels different. Turns require different entry and exit points, and wind can be a big factor. Just driving past a heavy-duty pickup truck towing a large RV inspires awe and a healthy respect for the sheer power of these machines.

Trucks like the 2024 GMC Sierra 2500 HD (signifying its heavy-duty classification) can tow an incredible amount of weight. The EPA classifies trucks with a gross vehicle weight rating (GVWR) above 8,500 pounds as heavy duty. That figure includes the curb weight of the vehicle, all passengers, and cargo. With a GVWR of 10,150 pounds, the 2024 GMC Sierra 2500 HD definitely qualifies in this category. Astonishingly, the Sierra 2500 HD can tow nearly twice its own weight, when properly equipped.

Check out this brawny pickup truck and see how it achieves its towing capacity and brute strength, straight from its engineers.

If you think trucks are getting bigger and stronger, you’re not wrong. Ten years ago, the 2013 GMC Sierra HD was capable of towing a maximum of 17,800 pounds. For model year 2024, the Sierra 2500 HD can tow up to 22,500 pounds, an increase of 4,000 pounds over the previous year. That’s a big jump.

Truck manufacturers are in tune with both the market and its customers, analyzing the competition before determining its goals for the next model. If a truck’s core customers never tow anything bigger than a small pop-up camper, then drastic increases in towing capacity aren’t necessary. In the case of the Sierra 2500 HD, GMC says the people who buy this truck mean serious business. Buyers want to be able to tow not merely a 15-foot camper but a large speedboat or a fifth wheel trailer with a big RV.

A fifth-wheel travel trailer is a large, heavy trailer that requires a fifth wheel hitch to tow. This kind of hitch requires a unique coupling mechanism to sit in the bed of the truck and requires that the towing vehicle has enough horsepower, torque, and body strength to handle it. The coupling device has a steel structure designed to meet a level of stiffness for the most balanced, safest ride possible. It also has rubber components between the steel parts to maintain solid handling.

At the top of the line, the GMC Sierra 2500 HD is equipped with a 6.6L turbocharged diesel engine paired with a 10-speed transmission. For 2024, it generates 470 horsepower and 975 pound-feet of torque at low revolutions per minute, which gives it a high level of pulling power.

The main test criteria for General Motors is the Society of Automotive Engineers (SAE International) SAE J2807 process, which is the industry standard for towing. Meeting SAE J2807 is not a requirement for any automotive company to follow. However, if you look at tow ratings posted online at various manufacturer sites you’ll find a footnote sharing whether it is following that procedure or not. The Big Three carmakers in America – Ram, Ford, and GM – generally do.

General Motors runs several types of tests on its designs, including a climatic wind tunnel that simulates a wide range of environmental conditions like wind speed, temperature, and humidity. Engineers place thermocouples, also called “thermoelectrical thermometers” all over the development truck – up to 200 of them, Norwood says – to collect data and communicate it back to the team.

GMC engineer Shawn Norwood says the automaker conducts other “more extreme” tests above and beyond the SEA standard. Some tests evaluate handling, and some check powertrain cooling to make sure the correct level of robustness is dialed in. In the heavy duty segment, 90 percent of buyers use their trucks to tow, so it’s an important metric.

“Our customers really push these trucks to the top,” Norwood says. “If they’re right on the edge [of its capacity], we don’t want to have any issues.”

If a driver pushes the truck past its capacity, they might overheat the vehicle and cause damage to the transmission or engine. The rear axle is also at risk of buckling if the load is too heavy, which could put the driver and its passengers (along with other vehicles on the road) in danger. GMC equips its heavy duty trucks with a visible and audible alert when the weight is getting close to the limit to avoid towing into the danger zone.

As more people take to the roads for camping, overlanding, and towing, GMC recognizes that there are a lot of new-to-towing drivers out there. To help those who don’t have much experience driving with a towed vehicle attached, in the last few years, the company has implemented technology called “Transparent Trailer” that allows the driver to “see through” the trailer using a series of stitched-together camera angles. As a result, drivers can be more confident on the road, which aims to make the experience more fun and less stressful overall.

Kristin Shaw has been writing about cars for Popular Science since 2022. She accrued extensive experience in the telecommunications, tech, and aviation sectors before she became an automotive journalist specializing in anything with wheels.