Are trailer side skirts in your future?

When it comes to cutting fuel costs and reducing emissions with trailer side skirts, for some fleets it boils down to: You can pay now, or pay later.

For a lot of fleets, it’s not a question of if, but when.

If you’re proactive, installing trailer side skirts now can offer savings of anywhere from 4 to 7 percent in fuel economy, depending upon the skirt product, as well as your fleets operating conditions. Your payback can be as little as 50,000 miles of trailer utilization.

You may be able to take advantage of government grants, as most side skirts on the market today are SmartWay-certified and eligible for grant consideration.

In its simplest form, the U.S. EPA’s SmartWay brand identifies products and services that reduce transportation-related emissions.

The fuel economy enhancements and long life of side skirts is why the EPA provided an $875,972 Diesel Emissions Reduction Act (DERA) grant to the Pacific Northwest Pollution Prevention Resource Center to help the company Interstate Distributors offset the cost of more than 2,000 sets of side skirts. Interstate Distributors is a provider of refrigerated and intermodal transportation services throughout the continental U.S., Alaska and Mexico.

Reactive Approach

If you’re reactive, and you travel to California, you’ll have to begin installing trailer aerodynamics eventually to be in compliance with the California Air Resources Board (CARB) Heavy Duty (Tractor Trailer) Greenhouse Gas Regulation. The rule already applies to 2011 model dry van trailers.

By 2013, any 53-foot trailer entering California must have SmartWay-certified aerodynamics and fuel-efficient tires, unless fleets sign up for optional phase-in compliance plans. For more information on the CARB rule, visit

Proactive Tactic

We’ve been seeing a lot of fleets becoming more proactive when it comes to their trailers, realizing that paying now has advantages. Either way, fleets will eventually win with better fuel economy and a fast payback.

If you do the math however, you will likely find that achieving improved aerodynamics sooner than later means you will start generating returns on the investment sooner than later.

Primary Challenge

When we came out with side skirts six years ago, our primary challenge was to prove to fleets that they saved fuel. We’ve seen up to a 7 percent improvement in fuel economy during track testing at constant highway speeds.

In real world fleet operations, fleets we work with typically report 4 to 6 percent improvements, depending upon their application and driving environment.

Average speed plays a large role because aerodynamic drag increases exponentially the faster you drive. For long haul fleets, side skirts are one of the lowest cost, biggest productivity performers on the market. They’re readily available on the aftermarket or can be installed on factory-ordered trailers.

On the aftermarket, these lightweight aerodynamic devices (our Aeroflex side skirts weigh 190 pounds) can be installed by factory-authorized shops, or installation can be done in-house by fleets with no special tools required.

Skirt Construction

The material used in the construction of side skirts can range from aluminum to fiberglass to plastic. Some are one-piece, others have multiple pieces. While they all work similarly, some save more fuel than others, and some are more durable, flexible and impact-resistant than others.

Without a flexible material and mounting system, steep loading docks and railroad crossings might damage or break a side skirt.

From a maintenance and repair standpoint, durability and impact resistance should be your top criteria when spec’ing side skirts. Side skirts should be worry-free.

As for maintenance, good quality side skirts require little, if any, attention. They should be annually inspected as part of the trailer’s normal inspection process.

It’s important to visually inspect the side skirt, fasteners and bracketry for damage and integrity – especially if the skirts bottom out frequently in your operations, or if you’ve had a hard side impact.

Again, damage to your side skirts will depend upon the material used in the side skirt, and on the bracketry and its flexibility. Some will take a hit better than others.

Further Efficiencies

As we move forward in the years to come, much has been made about the need to improve the fuel efficiency of tractors and trailers even further, and many millions of dollars have been earmarked by the U.S. Department of Energy to help the cause.

We, too, are involved and our goal is to realize a 15 percent improvement in fuel economy over trailers without fairings. This is a 6 percent improvement over what is commercially available now (through our side skirt and gap fairing).

This improvement would come from a combination of side skirts, gap fairings (streamlining turbulence between the tractor and trailer) and fairings at the end of the trailer.

But, in the here and now, products are available to streamline air, and your fuel bill, through side skirts. And, with a payback and ROI that can be measured in months, not years, trailer skirts are quickly becoming a common sight on highways.

Sean Graham is president of Freight Wing. Based in Seattle, WA, the company manufactures and distributes a full line of trailer side skirts, belly fairings, gap fairings and customized products for a variety of trucking applications. Freight Wing products are SmartWay- and Transport Canada-verified.