Every fleet operator wants to maximize load volumes — the more goods you haul, the more deliveries you can make. The more deliveries you make, the more you earn.
Trucks are designed to provide the power needed for hauling heavy cargo, but they do have limits. Exceeding these limits poses serious safety hazards. Extra weight increases braking distances and offsets the center of gravity, which can lead to rollovers.
So knowing the payload capacity of a vehicle is critical. The last thing you want is to unnecessarily endanger your drivers or others around them, risking life and limb, as well as valuable property.
In this article, we’ll explain what payload capacity is and how you can calculate it. We’ll also look at how a smart trailer solution from CalAmp can help you stay within legal weight limits and optimize load volume across your fleet.
What is payload capacity?
Payload capacity is the total weight a truck can carry. It includes the weight of the cargo on the truck bed and the passengers in the cab. No matter what you’re hauling, you must stay within the accepted limits.
Here are a few reasons it’s important to monitor payload capacity.
Overloaded vehicles are safety hazards
Weight limits exist for a reason.
Overloaded trucks take longer to stop, especially in rainy or snowy conditions. A driver may misjudge the braking distance and collide with the vehicle in front. Excessive cargo can also shift a truck’s center of gravity, which can destabilize the trailer and increase the risk of rollovers.
These risk factors make overloaded vehicles a safety hazard for your drivers and those on the road. In fact, data from the National Highway Traffic Safety Administration (NHTSA) shows that overloaded trucks contribute to an estimated 11 fatalities per year.
Excessive cargo causes stress on mechanical components
Exceeding a truck’s payload capacity places more stress on mechanical components like the suspension and brakes. This can lead to costly repairs and more frequent replacements.
Too much weight also stresses the tires, which can make them wear out faster and lead to blowouts. Blown tires can cause drivers to lose control of their vehicles. Tire debris may also hit other vehicles or even pedestrians, potentially leading to lawsuits.
Drivers can get hit with huge fines (and even jail time)
While truck drivers rarely load cargo, they can still get hit with huge fines or even jail time in some states if their truck is overloaded. Weigh stations will also stop overloaded trucks from continuing on their route, which can delay deliveries and strain customer relationships.
To mitigate all of these risks, you need to accurately track your payload capacity.
How do you calculate payload capacity?
Some manufacturers list payload capacity on a sticker or placard inside the driver’s door jamb.
Check the owner’s manual if you can’t find the vehicle’s payload capacity in the door jamb or if it’s difficult to read. Another option is to calculate payload capacity manually.
Use this formula:
- Payload capacity = gross vehicle weight rating (GVWR) - curb weight
GVWR is the maximum weight a vehicle can weigh when it’s fully loaded. It includes the combined weight of the trailer, cargo, and passengers. Look through the owner’s manual or check inside the door jamb to find a vehicle’s GVWR.
Curb weight is the weight of the vehicle. It includes everything it needs to operate, like fuel and equipment, but it doesn’t include cargo or passengers. You can find a vehicle’s curb weight in the owner’s manual. Alternatively, you can go to any weigh station. Be sure to bring everything you normally use to get an accurate number.
Next, subtract curb weight from the GVWR to calculate a vehicle’s payload capacity. For example, if a truck has a GVWR of 25,000 pounds and a curb weight of 10,000 pounds, its payload capacity is 15,000 pounds.
Payload capacity vs. towing capacity
Understanding the difference between payload capacity and towing capacity will ensure that you’re properly loading your vehicles and not putting your drivers at risk.
Payload capacity is the maximum weight a truck can carry in the cab and on the truck bed, while towing capacity is the amount a truck can pull or tow behind it on a trailer.
A vehicle’s towing capacity is typically higher than its payload capacity. The reason is simple: pulling an object is less work than carrying it. For example, imagine pulling a heavy rock in a wagon versus trying to physically carry it the same distance. The same principle applies to vehicles. As with payload capacity, there’s a maximum weight that vehicles can safely tow.
Use this formula to calculate towing capacity:
- Towing capacity = gross curb weight rating (GCWR) - curb weight
GCWR is the maximum combined weight of a vehicle and trailer. It includes the weight of your passengers, equipment, cargo, and “tongue weight” — the force that the tongue of a trailer pushes down on a hitch (roughly 10% to 15% of the total weight of a loaded trailer).
You can calculate GCWR by adding the GVWR of a vehicle to the gross trailer weight — the actual weight of a fully loaded trailer. Check the inside of the driver’s door jamb or the owner’s manual to find the vehicle’s GCWR.
Subtract the curb weight from the GCWR to calculate towing capacity. For example, if a truck has a curb weight of 5,000 pounds and a GCWR of 12,000 pounds, its towing capacity is 7,000 pounds.
How to stay within legal weight limits for large trucks
The Federal Highway Administration (FHA) mandates a gross weight limit of 80,000 pounds for all trucks. This limit was put in place to prevent overloaded trucks from damaging roads.
However, you can’t just haul 80,000 pounds of cargo and assume you’re in the clear. There are also regulations for the amount of weight you can place on each axle and the spacing between them when driving across a bridge.
Federal axle weight limits are:
- Single axle: 20,000 pounds
- Double axle: 34,000 pounds
Congress enacted the Bridge Formula to require longer wheelbases and establish axle weight limits to prevent overloaded trucks from damaging bridges. The Bridge Formula distributes weight across a longer distance, which places less stress on a bridge.
In the image above, both trucks weigh the same amount. However, truck B places more pressure on the bridge because of its shorter wheelbase. Use the Bridge Formula and check the weight limits for each state to ensure your trucks are within legal limits.
Long combination vehicles are subject to different rules
Long combination vehicles (LCV) are capable of hauling two full-size trailers. They’re designed to carry twice as much freight compared to conventional single-trailer trucks. As a result, they can exceed the 80,000-pound payload capacity limit.
Fleet operators with LCVs must follow all regulations, which can vary for each state. For example, Arizona allows a maximum gross vehicle weight of 129,000 pounds on certain highways, while Idaho allows 105,500 pounds on all national network (NN) routes. Some states, like California, don’t allow LCVs to operate at all.
The situation is further complicated by grandfathering clauses that allow LCVs only in certain circumstances. If you’re operating an LCV, contact your local authorities to verify your limits.
How to increase payload capacity
Most trucks are bound to their payload capacities. If you try to go around the predetermined ratings, you can end up on the wrong side of the legal system.
You may be able to increase the payload capacity of your fleet by adding another trailer, but this depends on whether your tractor can handle it in the first place.
If you have a powerful enough tractor and operate in a state that allows LCVs, you can adopt the different tractor-trailer configurations to increase the payload capacity of a single trip.
Truck drivers will need to complete an LCV driver-training program before they can legally operate an LCV. If you plan to add LCVs to your fleet to increase payload capacity, make sure your drivers have the required credentials.
If your current tractors aren’t capable of becoming LCVs and you don’t have any LCV-certified drivers, you might want to review the costs of this approach. It might be more cost-effective to buy or lease another conventional tractor/trailer combination and hire an additional driver.
How CalAmp can help
Maximizing payload capacity can boost your bottom line. But how do you keep your trailers within safe and legal limits? How can you identify underutilized assets and improve utilization?
This is where smart trailer technology comes in, a solution that uses telematics and sensors to capture trailer data in real-time. It can help fleet operators optimize asset utilization and improve productivity.
Improve trailer utilization with cargo sensing
CalAmp has partnered with Hyundai Translead to launch HT LinkSense. Ultrasonic sensors enable fleet operators to monitor trailer capacity and “see” how much space is available for each zone.
The solution integrates with CalAmp Telematics Cloud, allowing operators to gain real-time insights through the CalAmp Application — without having to manually check trailers in the yard.
With real-time visibility into capacity, fleet operators can tell which trailers are underutilized and instruct drivers on the road to pick up additional cargo. The CalAmp Application also integrates with Wex sensors, which can report suspension weight if they’re installed. Operators can instruct drivers to pull over and redistribute cargo if there’s too much weight on an axle.
Monitor tire temperatures in real time
Excess heat can increase tire pressure and cause blowouts. Wheel end temperature systems (WETS) can monitor the temperature of each tire.
Drivers can immediately pull over if the tires reach unsafe levels.
Increase cargo security with door sensors
Smart trailer solutions like CalAmp feature door sensors that can detect when a trailer door is open or closed. The sensors can even detect how long a door was left open.
These systems can help boost cargo security and prevent theft. If a trailer opens unexpectedly along a route, operators can contact the driver to check on the cargo.
Get started with smart trailer technology from CalAmp
To recap, payload capacity is how much weight a truck can carry on its truck bed and in the cabin. Monitoring payload capacity is essential to ensure you’re not overloading your vehicles and endangering those on the road. But it’s not always easy to manually calculate payload capacity, especially when you have delivery deadlines to meet.
CalAmp’s smart trailer solution features cargo sensing technology that offers real-time visibility into trailer capacity. This allows fleet managers to identify trailers carrying heavy loads and redistribute the weight elsewhere.
Request a demo to learn more about how CalAmp’s smart trailer solution can help with payload monitoring and improve trailer utilization.