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If your business relies on trucking for deliveries, paying attention to aerodynamic drag helps you save on fuel costs. Most drivers have at least heard of the term aerodynamic drag, but many are unaware just how important the overall shape and size of a vehicle is when navigating from point A to point B.

You can think of aerodynamic drag as mechanical forces pushing against your semi-truck in a high-speed setting. As your vehicle moves in a forward direction, it creates air resistance, which calls for a driver to increase acceleration. Overcoming aerodynamic drag might involve using up your fuel supply to move at a desirable speed. However, you can improve your fleet when you understand the types of forces moving along your vehicle and what you can do to promote proper airflow.

Generally speaking, a semi-truck that features a uniform build with rounded front-end surfaces can cut through the air more effectively compared to models that have rigid components near bumpers, grilles, and hoods. But you can improve aerodynamics on your semi-trucks by upgrading exterior parts so that your semi-trucks remain flexible and can adapt to sudden changes during transit.

How Does Aerodynamic Drag Impact Your Truck?

There is a direct relationship between aerodynamics in trucking and fuel-efficiency. To combat oncoming forces at the front of the vehicle, drivers must match or exceed the effects of drag by pressing down on the gas pedal. The less aerodynamic your semi-truck is, the more fuel you’ll need to burn to travel at a consistent speed.

Semi-trucks are some of the largest commercial vehicles seen on the road with box-shaped trailers, heavy mounted engines, and tractor-like cabins for pulling loads. While there is little you can do to modify the shape and size of your truck, knowing where pressure buildups occur on a semi-truck will influence component upgrades and attachments.

Two primary forces of aerodynamic drag that alter fuel-efficiency and vehicle performance are pressure drag and skin friction drag.

Semi Aerodynamics and Pressure Drag

Pressure drag is a result of compressed air particles moving from the front of a semi-truck to the back. Typically, a sensation known as turbulent flow takes place, as swirling winds spread outward along the vehicle’s cargo area. This pressure imbalance from the front to the back of your commercial vehicle is enough to create unwanted drag.

Semi-trucks are designed to transport loads, so most models are manufactured for maximum loading capacity. Pressure drag is somewhat inevitable when driving a stock vehicle because fleets are built for power rather than aerodynamic function.

Semi Aerodynamics and Skin Friction Drag

Skin friction drag refers to the surfaces of your semi-truck and any imperfections that interrupt the movement of air. You can think of the “skin” of your rig as any exterior components making contact with air particles. Anything that catches airflow and prohibits the distribution of pressure will result in aerodynamic drag.

One notable area of a semi-truck that alters resistance is the gap between the tractor and trailer bed.

How to Reduce Drag

As a business owner or fleet management personnel, you are likely always looking for new ways to improve the aerodynamic capabilities of semi-trucks. There are plenty of upgrade options on the market that install without the need for permanent exterior modifications. Change the shape of your vehicle using one or more of the following methods across your rig:

Vortex Generators

Vortex generators are commonly seen on aircraft, but the technology is slowly making its way to semi-trucks, trailers, and SUVs. These devices are small aerodynamic tabs that redirect airflow in areas that experience sudden drops in pressure. Place these installations near gaps on your semi-truck and along the back end of your rig to delay flow separation.

Drivers can attach vortex generators in seconds for stability, performance, and greater fuel-efficiency.


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Fairings and Side Skirts

Reducing semi-truck drag is as easy as mounting panels to your vehicle. Fairings and side skirts perform a similar function but go by different names based on their location. The goal of a fairing or side skirt is to guide air in a linear direction, helping you achieve handling control and, of course, less drag.

Fairing panels are also known as “rear tails” or “trailer tails.” Place these devices at the back end of your semi-truck to limit the pressure vacuum causing unwanted drag. Simply remove the technology from the cargo area when you’re ready to open doors for deliveries.

Semi-truck side skirts sit between sections of trailer wheels and stop air particles from hitting rear axles.

Drive Fenders

Semi-truck drive fenders install around your vehicle’s wheel wells. Aerodynamic shapes make it possible for air particles to roll past tires and move in a linear path down the sides of the trailer. Notice a difference in gas mileage, all while blocking rocks, dirt, and debris from kicking up.

Mud Flaps With Vents

Your fleet most likely left the production factory with rubber or PVC mud flaps. Use basic tools to swap these installations out for styles with vents allowing air to seamlessly pass through.

Wheel Covers

Your factory rims may have bumps, indentations, and holes where air can get trapped. Consider adding wheel covers to plug up these openings for significantly less drag near lug nuts and tires.

How Commercial Vehicle Aerodynamics Impact Fuel Economy

Drivers are often unaware of the role aerodynamics play in fuel consumption until they get behind the wheel of a vehicle that has upgraded features, attachments, or accessories. If adding eight wheel covers improves your fuel economy by just a quarter of a percentage point each year, you could save $1,000 per tractor according to the following parameters:

  1. Driving 100,000 miles each year
  2. Your rig gets 6 miles to the gallon
  3. Gas prices are $3 per gallon

Aerodynamic truck builds make it easier for a rig to limit drag so that drivers can coast and put less strain on engine components during acceleration. The less you have to use the gas pedal, the longer you can go without refueling.

Always Take Care of Your Semitruck Tires

Aerodynamic solutions contribute to fuel economy improvements, but you can boost efficiency even further by taking care of your semitruck’s tires. For more than 40 years, IMI has been dedicated to connecting customers to tire and wheel innovations that protect and preserve your investments. If you’re looking to keep your semitruck on the road for years to come, browse our solutions online, and complete a contact form for more information.