Axle Weight
Axle weight is the total load transmitted to the road through a single axle or tandem axle group. Federal law limits single axles to 20,000 lbs and tandem axles to 34,000 lbs, and states may impose stricter limits.
In Depth
Axle weight distribution is as important as gross weight. A truck can be under the 80,000 lb gross limit but still be overweight on individual axles if freight is loaded improperly. Proper weight distribution requires careful loading — heavy freight near the trailer's center of gravity.
Sliding the trailer tandems forward or backward adjusts the weight on the drive axles and trailer axles. Moving tandems back shifts weight from drives to trailer axles; moving forward shifts weight to drives. The fifth wheel can also be slid to adjust steer axle weight.
Improper axle weight distribution can damage road surfaces, increase wear on tires and suspension, and result in handling problems. Weigh stations check individual axle weights, not just gross, so a truck within gross limits can still receive citations for axle violations.
Usage Example
Example: 'My drives were at 36,800 lbs — 2,800 over the 34,000 limit. I slid the trailer tandems back 6 holes to redistribute weight.'
Related Terms
Gross Vehicle Weight Rating (GVWR)
GVWR (Gross Vehicle Weight Rating) is the maximum safe operating weight of a single vehicle as specified by the manufacturer, including the vehicle itself and its maximum cargo load. For combination vehicles (truck + trailer), the combined GVWR is called the Gross Combination Weight Rating (GCWR).
Bridge Formula
The Federal Bridge Formula (also called Bridge Formula B) is a federal regulation that limits the weight a commercial vehicle can carry based on the number of axles and the distance between them, to prevent damage to bridges and road infrastructure.
Weigh Station
A weigh station is a roadside facility operated by state departments of transportation where commercial vehicles are required to stop for weight and safety inspection. They verify that trucks comply with federal and state axle weight limits and safety regulations.
Scale Ticket
A scale ticket is a printed receipt from a certified commercial scale showing the date, time, truck identification, and recorded gross and axle weights. Scale tickets are used to document legal compliance with weight limits before entering a weigh station.
Frequently Asked Questions
What are federal axle weight limits?
Single axle: 20,000 lbs. Tandem axle group: 34,000 lbs. Gross vehicle: 80,000 lbs on Interstate highways.