Truck Size and Weight: Know Your Limits

For a trucking company, carrying more cargo typically means a more profitable haul. This leads many operators to try to load their trucks as close to the limit as possible. The increasing demand for just-in-time delivery has further pushed operators to attempt to optimize their haul to the legal truck carrying capacity. Understand how truck size and weight affect the limits can help you maximize profits while staying within the law.

The Current State of Semi-Truck Hauling Limits

Regulations exist to help protect roads, particularly the interstate highway system, from damage caused by excessively heavy trucks. Restrictions on weight keep trucks within safe operating thresholds.

To help ensure that trucking companies would be able to operate between states without undue burden from varied regulations, the federal government established a minimum-maximum limit. In other words, no matter which state you are in, on any U.S. highway the weight limit will never be lower than the federal limit. However, some states do have more lenient weight limits.

Federal Minimum Limits

The federal standards are fairly simple and every trucking company, operator and driver should know them. These are the current limits:

  • The gross weight must be less than 80,000 pounds.
  • A single axle should support no more than 20,000 pounds.
  • A tandem axle should support no more than 34,000 pounds.

As an example, a box truck with a single axle in the front and tandem axle in the rear can carry a total of 34,000 pounds. A semi-truck with a single axle and tandem axle under the cab and tandem axle under the rear of the trailer can carry up to 80,000 pounds. These weights need to be distributed properly to ensure the weight carried by each single or tandem axle does not exceed the limits.

Federal limits affect only federal-funded highways. That includes the interstates and national network of highways. As such, it is a good rule of thumb for most of the distance of the majority of routes. However, some state and local roads may have different limits.

State Variations

Several states allow semi-truck hauling limits above the federal limit. These states include Michigan, South Dakota, Maine, New Hampshire, Vermont and New York.

Keep in mind that any interstate trucking will typically need to adhere to the federal limits because most states use those limits. The major exception to this is between Maine, New Hampshire and Vermont, which neighbor each other and all allow at least 99,000 pounds.


One of the most important exceptions to the normal weight limits is bridges. These have special considerations for vehicle length. Congress enacted a bridge formula in 1975 that is as follows:

W = 500 [LN/(N-1) + 12N + 36]

In this formula, “W” is the gross weight of the vehicle, “L” is the length between the two outer axles and “N” is the number of axles on the vehicle. If the gross weight is under the bridge limit, you are allowed to cross it.

Preparing for the Unforeseen

The world of trucking can be complex with many regulations and expectations. It is easier to move forward confidently when you have the right insurance. Rev Insurance is a commercial insurance provider specialized in trucking companies. Call 800-347-5373 to learn more and get a quote.