Have you ever found yourself driving behind a pickup truck and wondered at the huge, rubber flaps hanging behind its rear wheels? Like a truck kilt or superhero cape, they may seem to separate the serious work trucks from the posers. But they are much more than a style accessory; these “mud flaps” are engineered to prevent the rear wheels from tossing mud or gravel backward and break your windshield.

Why do large trucks have flaps behind their wheels?

The flaps hanging behind the back wheels of a truck are called mudflaps. You will find them attached to most construction trucks, semi trucks, and even many pickup trucks. They are simply a shield to protect anyone driving behind the truck from flying mud or guard against stones.

So why do heavy duty trucks have mud flaps and cars do not? This might be because most cars are a bit lower to the ground. If a car’s rear tire tosses up a piece of gravel, this stone probably won’t be arcing high enough in the air to strike anyone’s windshield. But it may.

Why do construction vehicles and semi trucks have mudflaps?

One reason that you may see these mudflaps on construction vehicles, such as dump trucks, is the terrain they drive. Dump trucks spend a good amount of time driving on dirt or gravel, while navigating unpaved construction sites.

I suspect a third reason is liability. Most of the trucks listed above are commercially owned—and commercially insured. It makes sense that said insurance company would want to limit its liability, doing everything in its power to reduce the chance of damaging nearby cars. This is why many commercial vehicles may be required—or recommended—to wear mudflaps.

Why do small pickup trucks have flaps hanging behind their wheels?

While large commercial trucks may be required to have mudflaps to protect cars driving behind them, why do owners of private pickup trucks imitate this feature? It may be as simply be that the owners of pickups would love their vehicles to look more like commercial big rigs, so they imitate commercial accessories.

Some pickup truck owners outfit their vehicles with all kinds of “big rig” accessories. This might include a long radio whip to show they have a CB radio. This might include a row of yellow marker lights on the roof.

Wide mud flaps might well be another accessory that some pickup truck owners buy to make their vehicles look more commercial. It helps that you can buy mudflaps emblazoned with a variety of logos, from Harley-Davidson to trailer manufacturers to every automaker imaginable.

That said, mudflaps are a great accessory to see more of. The more pickup trucks wear mudflaps, the less chance some truck on a dirt road will toss a piece of gravel into the windshield of your car.

Next, find out why some pickup trucks have flat beds.