What You Need To Know About Semi-Truck Aerodynamics

Semi-trucks are common on highways, transporting our goods from point A to point B. What some people don’t know is that semi-trucks are not light on fuel use. So, research is continuously being conducted on how to reduce the fuel consumption of these vehicles. One area of this research is semi-truck aerodynamics.

What Is Semi-Truck Aerodynamics?

A semi-truck’s aerodynamics refers to how air collides with and moves around the truck’s surfaces while it’s in motion. Aerodynamic drag is the force that opposes the semi-truck’s motion and slows it down. While aerodynamic laws apply to all vehicles, the drag affects semi-trucks more due to their increased surface areas and heavy load.

Semi-truck aerodynamics has a huge effect on your trucking fleet, specifically their fuel consumption and wear and tear. To ensure that your semi-trucks are as efficient as possible, it’s crucial to understand their aerodynamics.

Factors That Affect Semi-Truck Aerodynamics

There are fuel saving devices for semi trucks available to help reduce aerodynamic drag around them. But to choose the best ones for your fleet, you should first understand some important factors that affect semi-truck aerodynamics.

The Front Of The Tractor

The front of the tractor affects how much drag is created on the trailer. The wind resistance created by this area can have a significant effect on fuel consumption and transportation costs. To reduce drag, you can install devices on your semi-trucks to manage turbulent flow around them.

The Gap Between The Trailer And The Tractor

The gap between the trailer and tractor can be a couple of inches or several feet long. The larger the gap, the more drag is generated. With increased drag comes increased fuel consumption.

The Sides And Underbody Of The Trailer

The trailer‘s sides and underbody affect aerodynamics because they influence how much drag-causing airflow is created around these areas of the semi-truck. In fact, the sides and underbody of the trailer are known to contribute up to 25% or an entire quarter of the aerodynamic drag on these cargo-carrying vehicles.

The amount of airflow created around your trailer depends on several factors including:

  • Trailer Height – The taller your trailer than the truck’s roofline, the more drag is created. The height difference would be another surface for the wind to push against.
  • Air Resistance – The greater the air resistance created by the trailer sides, the greater the need for the truck’s acceleration. This means you’ll have an increased need for fuel consumption.

The shape of the trailer and truck can be a factor in their aerodynamics. A rounded shape is better than a flat, boxy style because the former allows air to flow around more easily.

The Back Of The Trailer

The back of your trailer can have a significant effect on the overall aerodynamics of your semi-truck. If you’re looking for ways to improve fuel efficiency and reduce costs, then you need to consider the following:

  • Trailer Design – The shape of your trailer will affect how much wind resistance it creates while you’re driving down the road. The more rounded it is, the better it will be at reducing drag and increasing fuel efficiency.
  • Trailer Tails Or Rear Fairings – You can add fuel-saving devices to the end of your trailer, also known as boat tails. They work to decrease the amount of air turbulence at the back. In other words, they help reduce the drag coming from the low-pressure wake that forms behind the trailer.

With these tails attached to your trailer, it’s possible to decrease your fuel costs from 1% up to 5%. A bonus is that they’re fairly easy to install and detach as needed.

The Wheels Of The Semi-Truck

It’s easy to overlook the wheels, especially when considering semi-truck aerodynamics. However, it’s important that you don’t if you’re keen on making your semi-truck as aerodynamic as possible.

When the wheels of semi-trucks spin, they catch air and disrupt the airflow. This happens primarily because of their small crevices and large central indentations. And this airflow disruption adds to the already existing aerodynamic drag. To reduce it, you can use aerodynamic wheel covers, which are designed to close off all of these gaps or holes and guide the air past the tires.


As technology further advances, more efforts will be made in increasing aerodynamic features in semi-trucks and vehicles in general. For now, you can rely on modern design features and devices such as trailer skirts and tails or rear fairings, rear roof and cab extenders, wheel covers, vented mud flaps, and drive fenders, to improve semi-trucks aerodynamics.