Potholes: How They Form, and How to Protect Your Car

Stephen Fogel
May 10, 2018


If you’re lucky, you’ll see it looming ahead and have time to change lanes. But if it’s dark or you’re distracted, it gets a lot harder to miss. No matter where you live, this is the reality of potholes.

These road hazards are more than just annoying — they’re expensive. A 2016 AAA study found that potholes cost drivers in the U.S. approximately $3 billion each year, estimating that each repair runs $300 on average. How much you pay depends on how many potholes you hit — and what kind of damage they do to your car.  

Let’s look at how potholes are formed. You can also jump ahead to learn the types of damage they can cause and how to minimize it through proper maintenance and good driving techniques.

What causes potholes?

Potholes can form in a variety of ways. No matter where you live, you’re likely to encounter one at some point. Let’s look at some of the ways they’re created.

Erosion under the road

Underneath that smooth, paved surface, the earth erodes and moves over time, weakening support. The pressure created by traffic causes the road surface to crack and collapse, creating a small hole. As more and more vehicles drive over these small holes, they become bigger and bigger, turning into potholes.

Freezing and thawing 

Roads in cold climates get stressed by repeated freezing and thawing. Cracks, caused by pavement wear and erosion of the earth underneath it, allow water to enter when it rains or snows.

When temperatures are above freezing, the liquid water works its way through all these cracks and into the underlying layers of the road’s structure. And when the temperature of the road goes below freezing, the water freezes and expands by about 10%, making the cracks larger. Pieces of the roadway can come loose and break off. 

Eventually, the cracked pavement breaks up and becomes a pothole. This cycle speeds up during spring, when above-freezing days are often followed by below-freezing nights.

Extreme heat

In very hot climates, rain from a rare storm can work its way into the road surface, where it gets trapped. When the blazing hot sun starts baking the road, the water turns into steam, loosening pieces of the pavement and creating the beginnings of a pothole. Traffic does the rest.

Heavy traffic

There are approximately 300 million registered vehicles in the U.S., which means a lot of traffic on the road. This stresses the pavement, and is compounded by big rigs and other heavy trucks. The road surface starts to degrade, causing cracks and leading to the production of potholes.

Poor road maintenance

Without maintenance, roads wear out even faster. When city or state budgets are tight, small cracks in the roads go unattended, allowing them to become big cracks, and then big potholes.  

Get it diagnosed by a professional

How potholes can hurt your car

Potholes can damage all sorts of parts on your car, and can even cause accidents and injuries.

If you’ve hit one and noticed any of the following problems, you can get an estimate for your repairs before getting it fixed. Here are some of the more common issues these hazards create.

Tire damage

Your tires are the place where your vehicle meets the road. They’re your first line of defense — and the most vulnerable item when you hit a pothole. When you hit one, the hard edge of the pothole pushes your tire against the wheel. This can damage the tire’s tread, sidewall or internal belts. The tire can blow out completely during impact, or it may fail later.

If the tire survives the initial impact, watch for a bulge or bubble in the sidewall. There could be a gouge where a piece of the tread or sidewall was lost. Or you may start to feel a vibration through the steering wheel or the body of the car.

Solution: A damaged tire needs immediate attention — it shouldn’t be driven on. Put on your spare, if you have one, or have the vehicle towed to a mechanic. Tread damage may be repairable, but sidewall damage usually isn’t. 

Wheel damage

Today’s aluminum alloy wheels perform well overall, but a massive impact from a pothole can seriously damage them. The average distance between the tire tread and the wheel has decreased in the past few decades, making damage more likely. 

Pothole impacts create a huge amount of force, focused on a single point on your wheel, which can bend it so it’s no longer round. After such a big hit, you may notice a vibration as you drive.

Potholes can also crack your wheels. This may result in chipping, or even a piece of the rim breaking off. There could also be a hairline crack in the wheel, one that’s difficult or impossible to see. Keep an eye on the tire mounted on the affected wheel — it may start losing air.

Solution: Many bent wheels can be repaired if the damage isn’t too severe. Cracked, chipped or otherwise structurally compromised wheels are unsafe to drive on, and will need to be replaced. Ask your mechanic for a good wheel shop. While you’re at it, have him or her check for any other damage from the pothole.

Suspension and steering damage

Pothole damage can go way beyond your tires and wheels. Your suspension, which attaches those wheels to the rest of your vehicle, can also suffer. Today’s suspension and steering systems are complex mechanisms, with plenty of parts that can get bent, broken or knocked out of alignment:

When this happens, your car may pull to one side, or the steering wheel may point to one side when you’re driving straight. You might feel vibrations and hear odd sounds that you hadn’t noticed before. 

Solution: Have your mechanic inspect your suspension components for any damage. Damaged parts can be replaced with new ones, and the entire system can be realigned.

Exhaust system damage

Your exhaust pipes, catalytic converter and muffler are attached to the underside of your car, and can be menaced by potholes if they’re deep enough. Possible damage can include cracked pipes, dented and scraped converters and mufflers, and separations between their connections. You may notice that your exhaust suddenly sounds much louder, or there may be a dragging sound from a pipe that was knocked loose and is making contact with the ground. 

Solution: Call your mechanic immediately and schedule repairs. Any damage to your exhaust system can cause poisonous gases to leak inside your vehicle. If nothing is dragging on the ground, drive directly to your mechanic with all the windows open. If parts have come loose, have your vehicle towed instead.

Undercarriage damage

There are other components underneath your vehicle that can scrape against a bad pothole. Brake lines carry brake fluid to the brakes on each wheel. Parking brake cables may be routed under the floor. Fuel tanks can be mounted underneath. Your engine’s oil pan hangs down and is exposed. The floor itself can be punctured or torn. 

After a serious pothole, you may notice a fluid leak under your vehicle, or possibly smell gasoline. Your brakes or parking brake may stop working as well as you’re used to. These are bad signs.

Solution: Damage to your braking system, gas tank or oil pan are serious issues that will need immediate attention from a mechanic. If your vehicle’s floor is damaged, it should be repaired to prevent rust and keep water and exhaust gases from getting inside.

Body damage

If your car rides low or has additions like front spoilers and air dams, side skirts and rear bumper valances, these can get damaged by big potholes. The results can include scrapes, cracks or broken pieces.

Solution: While cosmetic damage to these low-hanging body parts looks awful, there’s not much of functional problem when a pothole smashes them. If the damage is severe enough, you might need to replace components like fog lights or parking sensors, if your vehicle has them built into its bumpers.

» LEARN MORE: Get an estimate for your car repair

potholes check

How to prevent and minimize pothole damage 

While some potholes are big enough to damage just about any vehicle, there are some precautions you can take to minimize damage if you hit one.

Tire pressure: Your top priority

If your tires don’t have the right amount of air, you’re much more likely to suffer serious damage if you hit a pothole. The air in your tires acts like a shock absorber between your tires and the rest of your vehicle. 

Without enough air, the jolts from pothole impacts are passed directly through your tires into the wheels, suspension and steering parts, and anything else connected to them. Low pressure can also result in increased tire damage, as the sidewalls get compressed and torn by the rough edges of the holes.

It’s also important that your tires are in good shape and have proper tread depth. To see if your tires are adequate, take a penny and stick it in the tread where it seems lowest, with Lincoln’s head facing toward the center of the tire. If any part of his head is obscured, you’re good; if not, it’s time for new tires. 

Check your tires at least once a month, when they’re cold. You can find the recommended pressures on a sticker in the driver’s side door jamb, imprinted on the tires themselves, or in your owner’s manual. While you’re at it, check those tires for any signs of pothole damage. Look for tears, cuts or missing chunks from the rubber on the tread and the sidewalls. Call your mechanic if you have any concerns.

Check your shocks and struts

Your car’s suspension is your second line of defense against pothole damage. If your struts or shocks are worn out from bad roads or high mileage, your vehicle won’t be set up to absorb the impacts. This can cause damage to your tires, wheels and suspension. Have your mechanic check whether these parts are in good shape, and replace them if necessary. 

pothole driving techniques

Driving techniques for potholes 

Of course, the best way to minimize pothole damage is to not hit any. Here’s how to avoid them as much as possible, and what to do if one is unavoidable.

Avoid distractions

Yes, this means not looking at your phone. It also means waiting to mess with the radio presets, put on makeup or eat those delicious-smelling french fries. You need to watch the road in order to see potholes in the distance.

Plan ahead

If you’re familiar with the roads you’re driving on, you probably know which ones have the worst potholes. Avoid those roads. A slightly longer route on smooth roads is a better choice for your car’s health — and your wallet. 

Scan ahead

Drive at an appropriate speed for conditions — don’t speed, and do slow down if it’s rainy or foggy. Leave plenty of room between you and the car in front of you. Look straight ahead and see if any other cars are taking evasive action. 

Be especially aware of puddles in the roadway during rainy weather. These can conceal potholes, both shallow and deep. At night, if it’s safe, use your high beams to see farther down the road. 

No sudden moves

If traffic is light, you might be able to maneuver around a pothole. But in medium to heavy traffic, it’s not a good idea. Be smooth and gradual with your steering when you try to avoid a pothole — don’t swerve or make sudden moves that can upset your vehicle’s balance. You must also be aware of any oncoming traffic, cyclists or pedestrians in the area that would make these moves unwise.

Don’t slam the brakes

Sometimes, you have no choice but to hit a pothole. When this is the case, slow down ahead of the hazard, if possible, but release the brakes before actually hitting it. Keep the tires pointed forward and grip the steering wheel firmly to keep your vehicle steady as you drive through the pothole.

In the event of a big hit, check for damage

If the impact feels serious, pull off the road in a safe place as soon as you can. Check your wheels and tires for any signs of damage. Shut off the engine and listen for the hiss of air escaping from a tire. If you have a flat tire, swap it for the spare or use your repair kit. Make sure nothing is hanging down from underneath the car. 

If everything seems OK, continue driving at a slower pace, and listen for any noises or vibrations that weren’t there before. If you don’t feel comfortable continuing, call roadside assistance, your auto club or your mechanic.

Stephen Fogel

About the Author

Stephen has been an automotive enthusiast since childhood, owning some of his vehicles for as long as 40 years, and has raced open-wheel formula cars. He follows and writes about the global automotive industry, with an eye on the latest vehicle technologies.

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