When it comes to moving cargo, truck owners should be aware of their vehicle’s capacity to handle weight. Proper operation begins with knowing the Gross Vehicle Weight Rating (GVWR). This rating refers to the maximum loaded weight under which a truck can safely operate as prescribed by the manufacturer.
What Is GVWR on a Truck?
The GVWR on a truck is defined by the weight of the vehicle itself, plus its maximum allowable payload in terms of passengers, cargo and accessories within the cab or bed. It excludes any weight towed behind the vehicle on a trailer. When an auto manufacturer rates a vehicle for its maximum GVWR, it is taking into consideration the load-bearing limits of the suspension system, frame, axles, wheels and other components that support weight. The GVWR for most types of cars can be found on the placard attached to the inside of the driver’s side door as well as in the owner’s manual.
In addition to the GVWR, knowing the curb weight of a truck is vital to understanding its ability to haul or tow. A vehicle’s curb weight is the weight of the vehicle by itself, excluding any added load from passengers, cargo, accessories or other items separate from that of the vehicle’s original manufactured parts and equipment. Curb weight does include the weight of gasoline, oil and other fluids necessary for operation. Curb weight is generally provided by the manufacturer, but you can also determine this at a vehicle weigh station.
How to Calculate Truck Payload Capacity
When the GVWR and the curb weight of a vehicle are known, you can determine both payload capacity and towing capacity. Payload refers to anything in the cab or bed that adds weight to the truck’s curb weight, including the passengers, cargo, and accessories such as toolboxes.
A vehicle’s payload can also include tongue weight, which is the weight exerted downward on the hitch ball by a trailer. The tongue weight is approximately 10 percent of the gross trailer weight (GTW), meaning a 5,000 pound trailer (with trailer load) adds 500 lbs. of tongue weight to a vehicle’s payload.
To calculate payload capacity, simply subtract the curb weight from the GVWR. Based on the formula, if a truck’s GVWR is 7,000 pounds, and its curb weight is 4,500 pounds, the payload capacity for the vehicle is 2,500 pounds. In most cases, the payload capacity can be found in the owner’s manual. Exceeding payload capacity can place added pressure on the shocks, suspension system, and the wheels, making it more difficult to safely control the vehicle safely.
How to Calculate Towing Capacity
While payload refers to how much a truck can carry, towing capacity is the maximum number of pounds a truck can pull behind it after factoring in its curb weight and any payload. A truck’s towing capacity will generally be much higher than its maximum payload limit because the majority of the weight is resting on the trailer’s axles instead of the truck’s axles.
To calculate towing capacity, a truck owner will need to know the vehicle’s Gross Combined Vehicle Weight Rating (GCVWR), not to be confused with GVWR. The GCVWR represents the total weight limit of a fully loaded truck plus a fully loaded trailer. Subtracting the truck’s curb weight and payload from its GCVWR defines its towing capacity.
Take for instance a truck with a GCVWR of 20,000 pounds. If it has a curb weight of 5,000 pounds and is carrying 3,000 pounds of payload, the towing capacity would be 12,000 pounds. For heavy towing maneuvers such as this, safety features such as Trailer Sway Control help keep loads from shifting laterally through lane-changes and crosswinds.
Why Knowing a Truck’s GVWR Is Important
It's important to compare cars before making a purchase to ensure you choose a vehicle that is capable of moving your cargo. Vehicles are designed under certain weight limits, so understanding payload and towing capacities is key to keeping a truck running safely. A truck operating over its GVWR or GCVWR can experience a significant reduction in handling and stability due to excess stress on brakes, tires, and chassis components. In poor driving conditions, the ability to maneuver safely decreases even further.
By simply heeding manufacturer weight guidelines, truck owners can prevent many accidents each year. In addition, hauling an improper amount of weight can result in excessive wear or damage to a truck’s frame, engine, and transmission. Be sure to consult your owner’s manual before carrying or pulling any load.
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