Home Trucking FAQs What are the weight restrictions on semi trucks?

What are the weight restrictions on semi trucks?

In 1973, in response to the many dangers posed by trucks, Congress passed a bill which set a number of restrictions on trucks. These rules apply to both large trucking companies and small owner operator businesses.

The action was intended to make trucks safer for the truck driver as well as other motorists. One of the restrictions involved load limits.

Federal Rules – Truck Weight

For interstate travel, there has been a load limit of 80,000 pounds [40 tons] since the bill’s inception. That is without any oversize or overweight permits.

The weight limit on single axles is 20,000 lbs, dual axles 34,000 and steer axles 12,000 lbs.

Federal Rules – Truck Size

On federal highways, semi trucks can be up to 102 inches wide and tow one 48-foot trailer or (2) 28-foot trailers. There is no height limit, except for structural clearances.

State Variances in Truck Weight

On highways that aren’t part of the federal interstate system, some states, such as Michigan, impose restrictions on the amount of weight between two axles that varies according to the season.

Some states allow temporary overweight permits, as well as oversized loads providing certain safety conditions are met.

Why Weight Restrictions Exist

Safety is the number one reason weight restrictions are in place.

The larger the load:

  • The greater the force of impact in a collision
  • The more likely the truck is to topple over
  • The more difficult it is for the driver to maneuver the truck
  • The more wear and tear on brakes and tires which are essential for safety

In the U.S., most long stretches of highway have random weight stations. Trucker drivers are required to stop and have their vehicle weighed at open weight stations.