Truck Weight Limits: Federal and State Rules
Federal law sets the maximum weights for commercial trucks on the Interstate System and the National Network. Axle limits and the bridge formula, not just gross weight, determine whether a load is legal. Shippers who routinely load heavy freight need to understand these rules — overweight fines are assessed against the carrier, but the freight doesn't move, and liability can flow back to shippers who provide inaccurate weight information.
Federal gross vehicle weight limit: 80,000 pounds
The federal maximum gross vehicle weight (GVW) on the Interstate Highway System is 80,000 pounds. This is the combined weight of the tractor, trailer, and cargo. A standard combination — a 34,000-pound tractor and 15,000-pound empty 53-foot dry van — leaves approximately 44,000 to 46,000 pounds of legal payload capacity, depending on the specific equipment.
The 80,000-pound federal limit applies on Interstates and the National Network. State roads may have lower limits; shippers whose deliveries require truck routing on non-highway roads should verify local weight limits with the carrier.
Axle weight limits
Gross weight is not the only constraint. Federal law also sets per-axle limits:
- Steer axle: 20,000 pounds maximum
- Drive axle (tandem): 34,000 pounds maximum
- Trailer axle (tandem): 34,000 pounds maximum
A load can be legal by gross weight but illegal by axle weight if freight is concentrated at one end of the trailer. This is particularly relevant for dense commodities — steel coils, machinery, heavy equipment — where the load's center of gravity affects how weight distributes across axles.
Drivers and carriers are responsible for legal axle weight distribution. Shippers who provide inaccurate commodity weight or density information, or who load freight in a configuration that makes legal axle distribution impossible, create liability that the carrier may push back to the shipper.
The bridge formula
Federal law includes a bridge formula that limits axle loads based on the distance between axles, not just the per-axle maximums. The formula is designed to protect highway bridges from excessive stress. It can restrict allowable weight below the per-axle limits in certain axle spacing configurations.
For standard 5-axle combinations (the most common truck-trailer configuration) on standard wheelbase, the bridge formula is typically not a constraint below the 80,000-pound GVW limit. For unusual configurations or extended wheelbase vehicles, it can become binding. Carriers who operate specialized equipment are responsible for ensuring bridge formula compliance.
Width limits: also federal, on the National Network
Federal law sets a maximum legal width of 102 inches (8 feet 6 inches) for commercial vehicles on the National Network. This applies to both the tractor and the trailer at their widest point, including mirrors. Standard 53-foot dry vans and most commercial trailers are designed to comply with this limit. Freight that overhangs trailer sides or requires oversized equipment must be permitted separately.
Height: state law governs, not federal
There is no federal height limit for commercial vehicles. Height restrictions are set by each state and apply to the road network within that state. Most states on the National Network allow loads up to 13 feet 6 inches. Some western states allow 14 feet or more. The legal height in any given state is determined by that state's regulations and the height clearance of the specific route, including bridges and overpasses.
Shippers with freight that may approach or exceed 13 feet 6 inches — industrial machinery, large equipment, high-cube loads — must verify height with the carrier and, if necessary, obtain state permits for the specific routing. Carriers moving oversized height loads are responsible for route surveys and permitting, but shippers provide the load dimensions.
Length: National Network maximum
Federal law does not set a maximum length for combination vehicles (tractor-trailer) directly, but does require states to allow standard combinations — specifically, twin 28-foot trailers or a single semi-trailer of 48 feet or longer — on the National Network. The practical standard for over-the-road dry van freight is the 53-foot trailer, which is legal on the National Network in all 48 contiguous states.
Overweight permits
Freight that exceeds federal weight limits can still move legally with overweight permits issued by each state whose roads are used. Permits specify the allowed weight, the required route, time-of-travel restrictions (many states restrict permitted loads to daylight hours), and pilot car requirements.
Permit loads require specialized carriers with experience in heavy haul and oversize operations. For oversize and heavy haul freight, see oversizeeasy.com. Standard FTL dry van operations — which this site covers — operate within federal weight limits.
Practical guidance for shippers
For standard dry van FTL, keep freight weight under 44,000 pounds to ensure legal payload with typical equipment. Confirm actual tare weight with the carrier for specific equipment if loading close to the limit. Provide accurate commodity weight to the carrier at booking — underestimating weight that results in an overweight fine is a shipper liability issue. Dense commodities loaded at one end of the trailer may require weight redistribution; confirm loading configuration with the carrier or carrier's driver before final loading.