Side Skirts For Your Trailer:

What You Need To Know

Technology That Lowers Your Fuel Costs

Side Skirts Are one option to reduce your operating costs

If you’re in the trucking industry, like any other business, you’re always finding ways to make more money. It’s more than just an accounting fact that one way to create a positive effect on your bottom line is to reduce your expenses and in the transportation industry, the biggest way to save money is to reduce fuel expenses. That’s what side skirts are all about.

What Are Side Skirts?

No matter where you drive these days, it’s becoming increasingly more common to see side skirts. You just may not know what you’re seeing.

Side skirts, often referred to as trailer skirts, are panels that are affixed to both sides and undersides of large trailers. The skirts are affixed to the trailer along the front and rear axles. The idea is to fill the gap and reduce air turbulence underneath the trailer. They are often made of hard plastic, aluminum or fiberglass to ensure durability of time and exposure to road conditions.

How Trailer Skirts Work

For generations now, engineers have studied flight and ways to make airplanes go faster. This has to do with the study of aerodynamics and the way air moves across various surfaces. If you look at the wings of an airplane, they are often flat on the bottom of the wings and rounded on the top of the wings. This helps improve lift which is essential for flight.

People often look at large commercial or military airplanes and wonder, “How does that plane, which weights thousands of pounds, get off the ground?” This has to do with the lift and the drag of the aerodynamics. Reducing drag and improving lift helps the plane fly.

The same information about the aerodynamics of flight has been used to study racing cars. When you look at Formula One racing cars, you see that they essentially have wings which help the car obtain incredible speeds but also stay on the ground. We may one day effectively have flying cars, but if a Formula One car suddenly took flight, it wouldn’t end well. That’s speaks to the essential need to understand aerodynamics.

Aerodynamic engineers have been working in the auto industry for decades now. They study the way air moves over passenger vehicles. It’s not uncommon for car commercials to show their latest model in a wind tunnel to emphasize how well the car moves on the road.

After studying the aerodynamics of planes, racing cars and passenger vehicles, engineers were hired to study how to take tractor trailer trucks and make them more aerodynamically sound. Imagine the size of the wind tunnel to have not only the rig but the entire trailer in it as well. This information was used to look at how air moves over the entire rig in order to identify ways to reduce drag and improve airflow. This is the research necessary to find ways to improve fuel consumption. It was essentially the birth of side skirts.

What the engineers discovered that when the air freely flows under and around the trailer, this produces a drag on the airflow. This slows the rig down and forces the engine to work harder. As the truck produces more energy to move the trailer, more fuel is used up in the process. By simply adding durable trailer skirts to both sides, this improves airflow, allows the engine to maintain a steady output and saves on fuel.

Since these studies were initially completed, side skirts have become common with trucking companies, fleet owners and even trailer manufacturers. Recognized and approved by the EPA’s Smartway Transport Partnership as an approved technology for improving aerodynamics, trailer skirts are eligible for funding under the Diesel Emissions Reduction Act. California even has regulations that require some form of aerodynamics on your trailer.

There was even a study done back in 2014 that looked into the adoption of technology that improved diesel efficiency. They found that side skirts were the most widely used technology. Back then, most of the larger trailer fleets used trailer skirts to improve their fuel costs. This technology is even more widely accepted today. This is part of why you see side skirts more frequently on highways all around the country.

Trailer Skirts Help Fuel Efficiency & Compliance

Like any business, the trucking industry looks at both fixed and variable costs. The cost of fuel is one of those variable costs that can make or break your bottom line. Installing aerodynamic technology on your trailers helps you improve your fuel efficiency as well as maintain compliance- especially in California. Imagine saving nearly 10% on your fuel costs. For most transportation related companies, deciding on installing something like side skirts or other forms of aerodynamic technology is an easy decision.

The Cost Of Side Skirts

Whenever considering putting trailer skirts or any upgrade to your trailer, it’s important to consider the return on investment or ROI. One thing is clear, any upgrade that saves you money actually pays for itself over time. It’s just important to do that math.

Of course, the cost of side skirts depends upon the vendor, but a common range can be anywhere from $1500 to $3500. If you consider that these attachments can save you anywhere from 5% to 7% on your fuel costs, it becomes easy to see how long it will take to recoup your investment. Usually, most trucking companies see these devices pay for themselves around a year or less.

Naturally, there are several factors involved in determining how long it will take to see a return on your investment. Once these systems are installed, you should begin to see a savings on your operating costs almost immediately; however, you have to factor in which aerodynamic systems you installed. For example, if you only use install one element and this saves you 1%-5% on your fuel, then you can calculate how long it will take to pay for the investment. If you install multiple aerodynamic devices, you increase your fuel savings by a larger percentage which means you will recoup your costs quicker.

A company that owns a fleet of tractor trailers would be able to save more money. The typical owner operator trucker may only have a single rig. He or she will see less of a savings on diesel than the owners of a larger fleet of trailers.

Given this, it’s easy to see how something like side skirts can be a smart investment. Not only do they add money to the bottom line in a fairly short amount of time, but saving fuel consumption is good for the environment as well.

Installation Of Side Skirts

Whenever a trucking company is considering installing new technology on their rigs, it’s important to consider various factors around installation. With side skirts, the actual time it takes to install them is fairly quickly.

As indicated, trailer skirts are made from a variety of materials but they are often modular in design. This means they can be put on in sections depending upon the length of the trailer. Trailer skirts typically weigh somewhere between 150 and 350 pounds which adds to the weight of the trailer, but considering the aerodynamic improvements, this weight is really negligible.

Besides better fuel consumption, there are other advantages to installing side skirts on your trailer. One study showed that trailers with side skirts saw a reduction in tire spray and the associated damage that can come from that. Also, rigs with trailer skirts reported an increase in stability when encountering dangerous crosswinds on the road. So, there can definitely be other advantages to installing aerodynamic technology on your trailers

Trailer Tails

While side skirts offer one option to improve the aerodynamics of a truck and trailer, trailer tails have become fairly popular in the past few years.

Sometimes referred to as a trailer tail, boat tail or rear fairing, these devices involve a set of collapsible panels on the rear of the trailer. Believe it or not, the patent for trailer tails dates back to 1898, so this is far from recent technology. Initially designed to improve airflow on trains, it was adopted to help other vehicles in the trucking industry.

Trailer tails reportedly help save somewhere between 1% to 5% in diesel fuel costs. The one drawback is that they do require some intervention from the driver in order to clear the way for loading and unloading.

Trailer tails can be paired and work together with other aerodynamic systems to further increase fuel savings. This is the idea that launched our entire company. SmartTruck lives and breathes to provide comprehensive systems that help you lower your operating costs.

Alternatives To Side Skirts & Trailer Tails

At Smart Truck Precision Aerodynamics, we have studied trucks and trailers. Our engineers have done their homework to provide the transportation industry with in alternatives to side skirts. We sell a variety of products that help incrementally reduce your fuel costs even more than traditional trailer skirts.

SmartTruck engineers have utilized the expertise of both CD-Adapco along with the University of Tennessee SIMCENTER to verify the performance of our aerodynamic products. Not only did they validate and approve of our aerodynamic systems, but as mentioned, our TopKit Fairing System was named a HDT Top 20 product for both 2015 and 2017. This means our aero systems have third party validation, so you can trust them to help save your operating costs.

Our Aerodynamic Products

We have a variety of aero systems you can select from in order to make your trailer more fuel-efficient. Here are the systems and the specs below:


Our most powerful aerodynamic system.

SmartTruck Premier Aero System

Our most powerful and advanced aerodynamic system that can deliver up to a 10% improvement in fuel economy. This is a complete system that catches the attention of most of the mid-sized to larger trucking companies. We install a variety of aerodynamic products on both the truck and the trailer- each system builds in more fuel savings. This durable system is EPA Smartway Verified and C.A.R.B compliant. While side skirts are helpful, this is one of the most comprehensive systems on the market to help you save diesel costs.

This system includes several features starting with the Aero Rain Guard which compresses and redirects airflow on the trailer roof to the rear corner and down into a low energy wake. We also install the Forward UnderTray which captures air and directs it below the suspension system. We provide two side fairings on the back of the trailer that redirect airflow around the back of the rig into the low energy wake. On top of these elements, we provide a limited lifetime warranty for these products.

At SmartTruck, we have the Premier LE and the Premier. The difference is that with the LE, you also get the Leadedge Top Fairing kit which is installed on the top of the trailer to close the gap of airflow between the trailer and the truck or between two tandem trailers.

None of the elements we install require any driver interaction. These systems are truly “set it and forget it”. Also, they never interfere with loading, visibility or loading docks. Because they’re so durable, they often last for years with no maintenance required.

SmartTruck Classic 

Our most economical undertray aerodynamic system for improved fuel efficiency



The classic aerodynamic system has a couple of the same features as the Premier. We install the forward undertray which captures air and directs it below the suspension. This system also includes the Aero Rain Guard mentioned above. The estimated fuel savings with just these two systems is estimated to be about 2%-6% which can really save you money over the long haul.





Forward UnderTray and Integrated Sled – Captures air and directs it below suspension.

Diffuser – Accelerates and injects air into low-energy wake behind the trailer.

Aero Rain Guard – Redirect high-energy airflow from roof down into wake.

Side Fairings (2) – Redirect high-energy airflow around back corners into low-energy wake.

SmartTruck TopKit

The smart alternative to side skirts

Named as an HDT Top 20 Product for two years and as recently as 2017, our TopKit Aero System is an innovative way to reduce drag without anything else. This system involves installing panels on the back of the trailer to redirect airflow. The cost of this system is comparable to side skirts and can help you save anywhere from 4%-6% in diesel costs.



  • Aero Rain Guard – Redirect high-energy airflow from roof down into wake.
  • Side Fairings (2) – Redirect high-energy airflow around back corners into low-energy wake.

SmartTruck LeadEdge Top Fairing

Closing the gap for better fuel efficiency

This aero system can save you anywhere from 1% to 3% in fuel by itself. It’s a durable component that has no effect on visibility or requires no maintenance. Installation time takes less than an hour, and we offer a limited lifetime warranty.



LeadEdge Top Fairing

Fleet Owners, Owner Operators & More

When considering an investment in aerodynamic technology for your truck or trailer, it’s important to weight out all the alternatives. Side skirts have been well adopted throughout the transportation industry, but now, there are alternatives to trailer skirts. In fact, there are entire systems you can implement- individually or as a complete system. These systems are environmentally friendly and add more money to your bottom line.

If you’re ready to start saving money on your diesel costs, be sure to talk to the professionals at SmartTruck. Consider all the options and we think you’ll make a decision to implement one of our aero systems. It could be one of the smartest decisions you could make. Don’t just settle with side skirts. Implement a system that pays for itself. Call SmartTruck today.


(888) 320-5970 (US)

(204) 229-7330 (Canada)

(888) 320-5906 (Technical Support)

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