Understanding GVWR, Payload, and Towing Capacity
What is GVWR?
GVWR (Gross Vehicle Weight Rating) is the maximum safe loaded weight of your vehicle or trailer, as determined by the manufacturer. This includes the vehicle’s weight, passengers, cargo, fuel, and any additional accessories.
You can find your vehicle’s GVWR on the placard located on the driver’s door pillar or in the owner’s manual.
Truck Classification by GVWR
The U.S. Federal Highway Administration (FHWA) classifies trucks into eight categories based on GVWR:
| FHWA Class | Duty Classification | GVWR Range |
|---|---|---|
| Class 1 | Light Duty | Up to 6,000 lbs. |
| Class 2a | Light Duty | 6,001 – 8,500 lbs. |
| Class 2b | Light Duty | 8,501 – 10,000 lbs. |
| Class 3 | Medium Duty | 10,001 – 14,000 lbs. |
| Class 4 | Medium Duty | 14,001 – 16,000 lbs. |
| Class 5 | Medium Duty | 16,001 – 19,500 lbs. |
| Class 6 | Medium Duty | 19,501 – 26,000 lbs. |
| Class 7 | Heavy Duty | 26,001 – 33,000 lbs. |
| Class 8 | Heavy Duty | 33,001 – 80,000 lbs. |
What is Curb Weight?
Curb weight is the total weight of the vehicle in its stock condition, including all essential fluids (fuel, oil, brake fluid) but excluding passengers and cargo.
What is GCWR?
GCWR (Gross Combined Weight Rating) is the total allowable weight of a vehicle and any trailer it tows. This includes the truck, trailer, cargo, and passengers. Unlike GVWR, which applies to just the truck, GCWR accounts for the combined load of both the vehicle and its trailer.
What is Trailer Tongue Weight?
Tongue weight (TW) is the downward force that the trailer exerts on the hitch of the tow vehicle. Proper tongue weight should be 10-15% of the total loaded trailer weight to ensure stable handling.
To measure tongue weight, use a specialized tongue weight scale or check the trailer’s specifications.
How to Calculate Payload Capacity
Payload capacity is determined by subtracting curb weight from GVWR:
GVWR – Curb Weight = Payload Capacity
Example:
A light-duty truck with:
- GVWR: 9,000 lbs.
- Curb Weight: 6,000 lbs.
- Payload Capacity: 3,000 lbs.
This means you can carry an additional 3,000 lbs. of cargo and passengers without exceeding the GVWR.
Payload Capacity When Towing
If towing a trailer, you must also subtract the tongue weight:
GVWR – Curb Weight – Tongue Weight = Payload Capacity When Towing
Example with a 2,000-lb. trailer (200-lb. tongue weight):
9,000 – 6,000 – 200 = 2,800 lbs. payload capacity.
Truck Add-Ons Impact Payload
Adding accessories such as a service body affects payload capacity.
For instance, installing a Reading SL service body (1,190 lbs.) onto a truck with:
- GVWR: 9,000 lbs.
- Curb Weight: 6,000 lbs.
Updated payload capacity:
9,000 – 6,000 – 1,190 = 1,810 lbs. payload capacity.
How to Calculate Towing Capacity
To determine your truck’s towing capacity:
- Find the manufacturer’s listed towing capacity (owner’s manual, door jamb placard, or manufacturer website).
- Compare it to the gross trailer weight (GTW) of the trailer you plan to tow.
- Ensure you don’t exceed the GCWR of your vehicle and trailer combined.
Why These Numbers Matter
Exceeding payload or towing limits can lead to:
- Reduced vehicle control
- Increased stopping distances
- Mechanical failures
- Higher risk of accidents
By understanding and adhering to these weight ratings, you ensure a safer, more efficient operation for yourself and others on the road.
Before loading up your truck or hitching a trailer, take a moment to verify your limits—your safety depends on it.