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Aerodynamic drag is a mechanical force generated by the truck’s movement through the air as it accelerates forward. It can be thought of as air resistance. Essentially, it is an opposing force that your truck needs to overcome in order to move forward. The stronger drags effects, the more energy the truck requires to move at the desired speed.



There are two types of aerodynamic drag your truck experiences: pressure drag and skin friction drag.

Pressure drag is the result of air particles that are compressed in the front of the truck and spread out in the rear. This happens when layers of air swirl away from the surface and create a phenomenon called turbulent flow. Since there is more pressure on the front than the back, drag occurs.

Skin friction drag is a result of air particles in the layer nearest to the truck’s surface colliding with the surface of the truck and slowing it down.

The effect of skin friction drag on tractor trailers is minimal. However, it is difficult to shape aerodynamically because of trucks’ size and weight, making pressure drag a significant problem. If you operate in cold conditions, the air is denser and aerodynamic drag is magnified even further.

The amount of work a truck must do to reduce drag creates a serious drain on fuel economy. The faster a truck goes, the greater the effect. The U.S. Department of Energy (“Technology Roadmap for the 21st Century Truck Program: A Government-Industry Research Partnership.” Technical Report 21CT-001, December 2000) found that 85 percent of the useful energy produced by your truck engine is energy used to overcome aerodynamic drag and rolling resistance. Additionally, 85 percent of the engine’s useful energy is used to overcome aerodynamic losses and rolling resistance.

Your Complete Guide to Reducing Aerodynamic Drag

Reduce your fleet's aerodynamic drag and increase fuel economy with our guide!

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There are several methods to reduce aerodynamic drag. A common solution is to add features to your truck to give it aerodynamic properties. Fairings are the most popular features of this type. Types of fairings include roof fairings, side fairings, underbody fairings, and end or tail fairings. Other aerodynamic additions to trucks include air dams, vortex generators, gap reducers, and nose cones.

All of these features are designed to turn your boxy, bulky truck from one that fights wind into one that “goes with the flow.” These additions change your truck’s shape so air flows over and around it rather than flowing into it or clinging to its surface. The result can be massive energy savings to the tune of hundreds of gallons of fuel a year. Fleet Owner provides this example

Changing from 6mpg to 10mpg for 1 diesel truck leads to 6,667 fewer gallons of fuel burned over a 100,000-mile year, which equates to a 40% reduction in costs and emissions.



A solution that is often overlooked when thinking about fuel efficiency is balanced tires. Low rolling resistance tires were created to address aerodynamic drag, but it is still important to make sure they are balanced. How do unbalanced tires negatively affect your bottom line?

  • Too much vibration
  • Uneven Treadwear
  • Increased fuel costs

If you’re going to invest in low rolling resistance tires and balance them, it’s important to balance them. Unbalanced tires cause vibration which will result energy loss, ultimately impacting the fuel consumed to drive the truck – leading to a reduction in fuel savings. This, in turn, cancels out the benefits of the low rolling resistance tires.

Using an internal balancer that adapts, like FLEXX , as another method to reduce aerodynamic drag is beneficial because it keeps your tires balanced by adapting to road, speed, and load forces. This will result in even tire wear increased fuel efficiency. A progressive Midwest fleet found that using FLEXX saved them $243,570 in fuel annually. Making sure your tires are balanced will multiply the other devices’ effects, compounding them to increase your overall fuel savings.

Case Study


Reducing aerodynamic drag is a key component in having a fuel-efficient fleet. If you’d like to learn more details on how to reduce aerodynamic drag within your fleet and the benefits of aerodynamic device adoption, download our guide!