Semi-Trailer Maximum Length

The maximum semi trailer length in the US is 53 feet or 16.5 meters. The height limit is 13.5 feet and the width cannot be more than 102 inches. The maximum gross weight is 80,000 lbs.

Purpose and Design

The semi trailer is a trailer that doesn’t have the front axle. Usually the trailer is pulled by a truck. The vehicle is used for carrying freight, goods and various types of cargo. The trailer is also known as an articulated lorry.

The road tractor is utilized to carry the bulk of its weight. The semi trailer has legs which are designed to hold the weight after uncoupling. Depending on the semi trailer length, another trailer’s tail may be used.


When the trailer is hooked up to a truck, it is called a semi trailer truck. They are also called tractor trailers, a semi, big rig or Mack trucks.

The Various Trailer Sizes

The size will vary depending on what it is designed to carry. Two types are widely used. One measures 8 ft (2.4 m) wide and the other 8 ft 6 inches (2.6 m) wide. This trailer is called the box or van trailer.

These come in various sizes, including 53 feet or 16.15 m, 48 ft or 14.6 m and 45 ft (13.7 m). Other van trailers measure 40 ft (12.1 m), 36 ft (about 10 m) 34 ft (10.36 m), 32 ft (9.7 m) and 28 ft (8.5 m). Some box semi trailer lengths are even less.

The Side Lifter and Other Types

The side lifter is equipped with hydraulic cranes. This feature does away with the need for a forklift, which are used for carrying and unloading cargo.

The double decker is equipped with a second floor. This feature can be fixed or hinged. The additional floor makes it possible to carry more items. For example, the typical trailer can contain 26 pallets. With a double decker, the capacity goes up to 40 or more.

With a drop-deck trailer, the floor will get down one level after the tractor’s clearing. The bus bodied trailer is connected to the tractor. This is used to make a trailer bus. The curtain sider is just like the van trailer.

The big difference is that the sides can be moved. It is water resistant and comes with enforced fabric. This design is popular because it is very secure and can be used in different kinds of weather. At the same time it is as easy to load as a flatbed.

Other Variants Used

The reefer is just like a box trailer except it has heating and cooling features. It is used for transporting ice cream. The dry bulk is like a giant tanker. It is used for carrying flour, sugar and other powder substances.

The semi trailer length mandated in the US does not necessarily apply in the UK and other countries. Also, some trucks can go over the weight limit provided they get a special permit. Methods of acquiring the permit vary per state.

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