Road Noise – What Is It and How to Reduce It!

As the temperate and crisp spring peeks its cordial head around the metaphorical calendar corner, we prepare our wardrobes with eager joy. Once the days of brutal winter chill begin to fade, we will lurch to our closest shorts and t-shirts, regardless of the actual warmth in the weather. And when it comes to driving, spring means throwing the windows down, the sunroof open, and letting the fresh air finally fill our chilled lungs. With all of that openness comes the increase of road noise, the silent (or not-so-silent) annoyance of car travel.

Here’s the thing: road noise can become disruptive even if you don’t have your windows down. If there are enough audio leaks in your vehicle, driving down a normal road can be a noticeable nuisance.

We’ve all been there. You are driving, enjoying a casual conversation with your copilot like the daily life of Han Solo and Chewbacca when, from the gravel of a dusty road, sound engulfs your car with talk-stopping decibels. Things become too loud for comfort and road noise becomes the only thing you can think about. Though it may not be outright dangerous, it’s obnoxious and distracting.

If your car is significantly loud while driving, you may need to work to reduce road noise. Here’s how:

What Is Road Noise?

Let’s get scientific!

In its simplest form, road noise is the noise that echoes within your car from the act of driving. Tires on bumpy roads, the active whirring of a working engine, wind passing through cracked or open windows. It’s the unavoidable noise of moving in a vehicle. If you have driven a car past a neighborhood speed, you have heard some sounds from the overall motion.

And while these causes are technically noises from the road, they aren’t the actual main pillar holding road noise to our ears. At the end of the day, the relationship between the tire and the road is the main factor of the sound, not the array of other motions. That humming and vibration that causes conversations to stall, that’s all tire.

For the true scientific explanation, I’ll leave it to the experts. We’re just a car-selling website, after all.

Quote from Physics Today:

Noise heard outside the vehicle is largely governed by different texture wavelengths than those responsible for the noise heard inside the vehicle. At highway speeds, texture with significant amplitudes and wavelengths of about 10-50 mm is largely to blame for noise that is readily radiated away from the vehicle; texture with wavelengths of 20-200 mm is responsible for in-vehicle noise. In both cases, the dominant noise-producing mechanism is termed impact. As the tire rolls over the pavement, displacements in the road surface or tire-tread pattern create vibrations in the tire structure. Those vibrations, in turn, lead to acoustical energy being radiated from the tire-tread elements and sidewall. The impact mechanism is most evident in the characteristic roar of “knobby” tires found on some off-road or heavy commercial vehicles.

Despite having a full physical definition of the sound, finding a way to combat it seems impossible. Physically impossible (by its most literal definition).

Theoretically, if creating a perfectly flat or smooth road was possible, it may reduce noise a little, but it would only raise driving danger. The lack of friction and texture would make driving nearly impossible. The need for tire texture and tread is obvious. Without it, any driver would be in direct danger.

Put into laymen’s terms: it may be impossible to eliminate road noise. Tires and roads must have texture and friction to operate correctly and safely. The only way to eliminate noise would be to eliminate the physics keeping drivers in control. Even then, there’s still a possibility that the two different objects would make a sound rubbing together.

How Can You Reduce Road Noise?

If it’s entirely impossible to get rid of driving sounds, are there ways to reduce them? If your car is especially noisy during drives, you may just be looking for an overall reduction, not an outright elimination.

Luckily, there are a few ways to reduce road noise. Let’s get into them!

Keep Your Tires in Check

If the creation of road noise relies entirely on the surface you are driving on and the tires on your vehicle, you can work to lessen one of the two factors. You can’t fix every bumpy road, but you can make sure you have quality and intact tires on your vehicle.

Consequently, the sound created by the tire can be reduced through a few different factors. One, a narrower tire will make less noise. Two, smaller grooves and space between the grooves will cause less friction. Three, softer tires allow for more pliability and less noise.

It’s also important to note that the integrity and wear of the tire are important here, too. A worn-down tire will have a reduction of all the aforementioned three factors, making the sound much louder.

If you have a normal-sized car, you are in luck. Your standard all-weather tires should be your best bet. If you have bigger tires, you may need to reduce their width to lower the sound.

Overall, if your tires are worn or too big, you will have a significant noise increase. Keep an eye on the durability and condition of your tires. For your safety, you should never drive on worn tires, anyway.

Get Vibration Dampeners

At the end of the day, the transportation of sound involves vibration. Regardless of what is causing the noise or what medium the noise is going through, the lowering of the vibrations will lower the volume. Therefore, you can always reduce how much you hear of the sound instead of attempting to lower the source of the sound itself.

Brands like Dynamat have created sound-dampening mats for vehicles. These floor mats (or overall mats) are often thick rubber. The introduction of thick mass, like rubber, into the pathway of sound will significantly reduce it. Therefore, placing the mat on your car floor (right above the source of the sound) lowers it.

While expensive, the mats work well, especially if getting narrower tires isn’t an option.

Soundproof Your Trunk and Doors

Much like the above tip, you can use soundproof materials to lower the sound transmission through the other main leaking points in your vehicle.

Your doors are windows are obvious. They are the thinnest material between you and the outside world. Henceforth, sound can sufficiently travel through the open cracks and crevices, creating a much louder drive. So, using materials like Dynamat soundproofing strips could help lower the noise travel. Just make sure they don’t cover necessary parts of the door, interfering with functionality.

The trunk, on the other hand, isn’t as obvious. Scientifically, it makes sense. A large and empty trunk acts as a cavernous diaphragm, amplifying the sound from underneath it.

If you don’t usually have a full trunk, you may want to place some soundproofing mats (like the one for your interior floors) at the bottom of the trunk. This will significantly reduce road noise. Seriously.

If you have a tiny trunk, you may not need to do anything. A smaller trunk shouldn’t have much effect on the overall sound.

Don’t Fall for Scams

At the end of the day, it’s important to note the impossibility of eliminating road noise. Unfortunately, there is no miracle cure that will make your vehicle sound like the inside of a recording studio. Through the nature of physics, your car will always have some noise while operating.

If a soundproofing or wind-stopping product says it can fully eliminate road noise, it’s a scam. Don’t waste your money on it.

Make sure your tires are in good shape and cover your floors, cupholders, and trunk floor to greatly reduce noise (but not get rid of it).