Your tire’s sidewalls are, as the name implies, the exterior sides of your car’s tires. While you may not think of the sidewalls as being a particularly important area of your tire, the truth is that your tire’s sidewalls are quite vulnerable and damage to the sidewall is often worse than damage to the tread.

A tire with a damaged sidewall is in far more danger of bursting than a tire with damaged treads. This damage might take the form of either a gash or a bubble in the tire’s sidewall. There’s a considerable level of danger when driving around on tires with damaged sidewalls, and you should never knowingly do so.

In this article, we’ll be taking a closer look at tire sidewall damage and sharing with you what you need to know about your tire’s sidewalls. We’ll be covering what causes tire sidewall damage, how to know when to replace a tire, and whether or not tire sidewall damage can be fixed, among other things.  

Related: Why Does Gas Mileage Drop With New Tires?

What Is My Tire’s Sidewall?

As we’ve mentioned, your tire’s sidewalls are the sides of your tire. Tire sidewalls have two functions; they protect the vulnerable cords that give the tire its structural integrity, and they’re used as a surface to display relevant information about the tire.

While we’re on the subject, let’s quickly talk about how to read tire codes. The text written on tire sidewalls can be confusing to read at first, but once you figure out how the code works, it’s actually pretty straightforward.

Let’s take a look at an example tire code, P205/55 R16 91V. Here’s how the code breaks down:

• “P” refers to the type of tire. In this case, “P” is short for “P-Metric”, which is a set of standards for tires in the United States.
• “205” is the width of the tire in millimetres. 
• “55” is the aspect ratio of the tire. This refers to the ratio of the height of the tire to its width. In this case, the height of the tire is 55% of the width of the tire. The lower this number is, the lower the profile of the tire will be.
• “R” stands for “radial”, which refers to how the cords inside the tire are arranged.
• “16” is the diameter of the wheels that fit inside the tire.
• “91” is the load index, which refers to the maximum amount of weight that the tire can support. For example, a load index of 91 means that a tire can support a maximum of 1,356 pounds.
• “V” is the speed rating. In this instance, “V” indicates that the tire should not be driven faster than 149 mph.

What Causes Tire Sidewall Damage?

There are several ways that your tire sidewalls can become damaged. Let’s go over each of them and explain how exactly they affect the condition of your tires:

Physical Impacts

Physical impacts caused by driving over obstacles such as potholes and curbs are one of the main causes of tire sidewall damage. Even though it’s the tire treads that are subjected to the most force in such instances, the resulting damage is often most visible on the sidewall.

This is because with a hard enough impact at the right angle, the cords that hold the tire together can break. When the cords break, air inside the tire starts to leak out between the tire’s layers, which causes the sidewall of the tire to start bulging out.

If you notice that one of your tires has developed a bulge in the sidewall, you should have that tire replaced immediately. Continuing to drive on a tire in this condition is a serious safety risk, as a tire that is damaged in this way could experience a blowout at any given moment.  

If you scrape your tire up against a sharp object, it’s possible to cause a gash in your sidewall as well. Unless this gash is very small, you’ll need to replace your tires in this case as well.

Tire Wear

As tires are used, they are constantly wearing down. Over time, tiny bits of rubber are shorn off the tire thanks to the friction generated by spinning against the road. With a sufficient amount of time, enough rubber will wear off the tire that the treads get ground down into nothing. Tires in this state are referred to as “bald” tires.

Aside from providing traction, having an adequate amount of tread on your tires also helps prevent your tires from overheating. The more bald your tires are, the less they’re able to resist heat. Overheated tires degrade way more quickly than normal, so the longer you drive on balding tires, the greater the damage you’ll cause to them.

In particular, when the tire cords get overheated, they’re at risk of falling apart. Since the cords are vital to the structural integrity of the tire, this is obviously not something you ever want to have happen.

Tire Age

All tires start degrading the moment they’re made, even if they’re not actually being used. This is because when rubber is exposed to any kind of heat and oxygen, it starts losing its flexibility and becoming brittle. 

Most tire manufacturers state that tires generally last between 6 and 10 years, as long as they’re not used. Running tires that have been sitting around for a long time is a serious safety risk, even if the tire tread is still sufficiently deep and there are no bulges in the sidewall.

Old, brittle tires are much less resistance to heat than new tires, and when driving on old tires there’s the chance that the plies within the tires will separate from one another. All of this means that driving on old tires leaves you at a much greater risk of experiencing a blowout.

Underinflation

Tires naturally lose a small amount of air over time, but if you drive for too long on a tire that is significantly underinflated you risk destroying your tire entirely.

When a tire is inflated properly, the air pressure inside it is one of the main things that helps it support the weight of the vehicle. The air keeps the tire fairly rigid and prevents it from flexing too much. 

The sidewalls of underinflated tires are far more prone to flexing, and as a result, they also heat up a lot more quickly than properly inflated tires. Thanks to this, underinflated tires are much more prone to issues caused by overheating. 

Tire Overload

You should never put more weight on a set of tires than it’s designed to handle. Like driving on underinflated tires, driving on overloaded tires causes the tires to overheat more quickly, which as we’ve discussed can severely degrade your tires.

If you’re unsure of what the maximum weight your tires can handle is, just look on the side of your tire from the load index number. Figuring out exactly how much weight your tires can hold based off of the tire load index can be tricky, so you might want to refer to a tire load index chart to make things easier on yourself.

Manufacturing Defects

This isn’t the most common reason for tire sidewall failures, but it certainly happens enough to make it worth mentioning. Occasionally, you might wind up with a tire that just hasn’t been built to the usual standards of quality.

Tires can fail due to defects in the design of the tire itself (such as tires that inherently lack certain components or materials that would otherwise make them more sturdy) or defects during the manufacturing process (which are usually due to simple error or a lack of quality control). 

Unfortunately, if your tires are indeed defective, no amount of maintenance or careful driving is going to make them last, and you should have any defective tires swapped out for properly-made ones as soon as you can.

Manufacturing defects will almost always get re-called, so if you suspect your tire may be “weak” due to manufacturing defects, visit the NHTSA.GOV Website and search for you tire brand to make sure.

Can Tire Sidewall Damage Be Repaired?

In short, no. If your tire’s sidewall has been damaged to the point where it would actually need repair, then you need a new tire. Damage to your tire’s treads can be repaired in some cases, but damaged sidewalls can’t be.

This is because the cords of the tire are located under the treads, and when plugging a hole in the treads, the cords give the plug the support it needs to stay in place. There are no cords in the sidewall, however, so it would be impossible to actually install a plug there to begin with.

In addition, if you notice that your sidewall is starting to budge, this means that the cords inside the tire are starting to come apart. When this happens, it means that your tire is already damaged beyond repair and should be replaced.

In short, you should have your tires replaced if you notice sidewall damage of any kind. The only exception is if the damage is really superficial, in which case you can probably keep driving on that tire for a while as long as you keep an eye on it to make sure that the damage doesn’t get significantly worse.

Is Driving With Tire Sidewall Damage Safe?

NO! Driving with a damaged tire sidewall is unsafe for multiple reasons, including the fact that sidewall damage severally degrades the integrity of the tire, much more than thread damage, because of the way tires are built (See Above)

In fact, driving with any sort of tire damage or defect is unsafe. According to the National Transportation Safety Board, around 33,000 accidents occur each year as a result of tire problems. Furthermore, as many as 2,000 of the incidents are the result of tire sidewall problems.

Is Tire Sidewall Damage Covered Under My Warranty?

Tire sidewall damage, or any damage to your tires in general, is almost never covered under your vehicle warranty. If you want coverage for your tires, you’ll have to get a separate warranty to cover that. Tire warranties are usually offered by the tire manufacturers themselves. The type of coverage you get also depends on the specific warranty you buy.

Some warranties do indeed cover you for any damage sustained to your tires from potholes or other road hazards, but these warranties are typically only valid for a relatively short period of time after you buy the tires. In addition, your tires are only covered if they are damaged beyond any repair.

Other warranties, on the other hand, might only cover tires that wear out prematurely, or they might only cover issues specifically stemming from manufacturing/design defects.

In most cases, people who buy tire warranties aren’t usually able to take advantage of them, since it’s hard to meet the criteria that would make them eligible to claim the warranty to begin with. Unless you live in an area where the roads are in exceptionally poor condition, a tire warranty probably isn’t worth it most of the time.

You can look at Costco’s tire warranty to get an idea of what’s covered if you decide to get a tire warranty.

Is It Illegal to Drive with Damaged Sidewalls?

In many places, yes, it is illegal to drive any vehicle if it visibly appears to be in dangerous conditions. This includes vehicles with sidewall damage to their tires, but also vehicles with underinflated or balding tires.

Not only is driving around on damaged tires a bad idea from a legal standpoint, but it’s also unsafe and not very cost-effective. Properly maintaining your tires and your vehicle in general not only makes it safer to drive, but also keeps repair costs down and helps preserve more of the car’s resale value.

In short, it’s always a good idea to keep an eye on your tires and replace them before they get too worn out.