Width Of Semi Trailer: How Wide? Basic Information

Width Of Semi Trailer How Wide Basic Information

The public typically uses the term “semi trailer” to describe the typical box trailer-tractor cab combinations seen traveling down the highway, but in actuality, this term refers to a wide variety of trailer types. Understanding semi trailer dimensions specifically and what each type of trailer can tow is essential for those who work in the sector.

The following guide will go over the common width of semi trailer. Additionally, a few significant rules regarding the size and weight of semi trailers will be discussed, assisting operators in determining when state-specific permits are necessary. 

What Is The Trailer For A Tractor Standard Width?

At the moment, the minimum requirements for tractor-trailers are set by the federal government of the US. Only 102 inches is the width’s maximum. A tractor-trailer can only be 108 inches long in Hawaii, so take note of that.

The established width of a highway travel lane, which is based on physical constraints, determines this maximum limit, which varies slightly from state to state in some cases but is almost universal.

It’s crucial to realize that the 102-inch restriction applies to both the Interstate system and national highways. The maximum width for surface streets is just 96 inches, but this varies from state to state and even from city to city. Prior to hauling an oversized load, careful planning and research must be made to ensure compliance with restrictions and other factors.

A Tractor Trailer May Be Wider

The federal maximum indicates that a semi trailer’s maximum width of 102 inches may be exceeded, but only with the proper permits. Keep in mind that cargo, not trailer width, is what is really being discussed here. The majority of trailer manufacturers adhere to the maximum width recommendations, but in some circumstances, wider loads—bulky objects that extend well beyond the sides—can be supported by the trailers.

A semi that is enclosed by walls ensures that the upper limit is never reached. However, that maximum can be exceeded, at least in part, with an open configuration, like a flatbed or gooseneck.

Although hauling such cargo necessitates special precautions, such as pilot trucks and oversized cargo signage, as well as special permits issued by the state through which the tow is being towed, oversized loads are not uncommon on US roads.

Width Of Semi Trailer How Wide Basic Information
Width Of Semi Trailer: How Wide? Basic Information

The Most Common Types Of Trailers And Their Dimensions

Flatbed Trailer Dimensions

One of the most popular designs of semi trailer used to transport equipment is the flatbed trailer. They are adaptable in that they can transport an LTL load, such as a forklift or large machinery. When it’s an LTL load, the driver is able to transport multiple pieces of freight from various clients, which can help cut costs. See below for the flatbed trailer’s measurements.

Max Length: 53 ft.
Max Width: 8.5 ft.
Max Height: 8.5 ft.
Max Weight: 48,000lbs

Step Deck Trailer Dimensions

Step deck trailers have two levels and are used as semi trailers. Taller equipment can be transported without obtaining additional permits thanks to the step deck trailer’s lower deck. The upper level deck of step deck trailers makes it possible to transport multiple pieces of equipment as well. The step deck trailer measurements are listed below.

Upper Deck Length: 11ft.
Lower Deck Length: 37 ft. to 41 ft.
Overall Length: 48 ft. to 53 ft.
Upper Deck Height Maximum: 8’6 ft.
Lower Deck Height Maximum: 10 ft.
Max Width: 8’6 ft.
Max Weight: 48,000lbs


The U.S. government-established standard for semi-trailer dimensions. Department of Transportation permits lengths between 48 and 53 feet. The federal government has established that as the norm for use on the nation’s highways.

While length and height can vary, width is more standardized. The semi-trailer’s typical dimensions are:

  • Length: 48 – 53 feet (576 – 636 inches)
  • Width: 8.5 feet (102 inches)
  • Height: 13.5 feet (162 inches)

The right dimensions and load capacities are essential when selecting a semi trailer to complete the task at hand. Transwest is here to help you find the trailers you need to finish the job, whether you’re moving goods locally or across the country. For more information on purchasing additional trailers for your fleet, get in touch with our knowledgeable staff right away.

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