When there’s damage to the sidewall of your tire, you’re almost certainly going to need a new one.
Your tire’s sidewall might be damaged by hitting a curb, improper wheel alignment or balancing, foreign bodies such as glass shards or nails, and more.
The damage isn’t always visible. Sometimes, while everything might appear fine on the outside, the inside of the tire is crumbling away.
Tires are one of the most critical parts of the car. If you can’t grip the road, you can’t start or stop. Punctures cause fuel inefficiency and potential damage to your suspension and wheel. Sudden blowouts quickly lead to a sudden loss of control and potential danger for you, your passengers, and others on the road.
As a result, you must repair all tire damage immediately; however, damage to sidewalls is terminal for the tire. You’ll need to get a new one as soon as possible.
In this article, I’ll be explaining how the tire’s sidewall is structurally integral and, therefore, why you need to get any damage fixed as soon as possible.
- The basics of tires
- Sidewall damage causes
- Inspecting sidewall damage
- New tire cost
- What is a sidewall bubble?
- Is a spare wheel safe?
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What Does A Tire Do?
Okay, I admit, there’s probably not too much you don’t already know about what a tire does, and it seems like quite a silly question. The reason I feel it’s important to address, though, is that, with this information in mind, it’s much more straightforward to grasp the importance of maintaining good tire “health”.
A tire is the point of contact between the car and the road, gripping it. Traditionally, it’s made of rubber and filled with air — nothing new there.
When a tire goes flat, bursts (or “blows”), or is overinflated (which can be just as dangerous), that’s all lost. You don’t have any grip, and, straight away, components in the steering and suspension systems begin to get damaged.
If the tire blows completely, suddenly you’ve got a car connected to the road solely through the bare metal of the wheel. As you might be picturing, sparks would fly, the car would struggle to get moving and to stop, and you’d lose control exceptionally easily.
Damage to the tire’s sidewall can easily lead to this – it blowing out.
Although it’s obvious to talk about, I hope it illustrates how vital tires are to both safety and standard running conditions for vehicles. As such, if your tire is on the way out, it’s dangerous. Not just to you, but others in your car, others on the road, and pedestrians.
You have a legal and moral duty of care to keep people safe. The average car is a ton and a half of metal moving at speeds that can seriously damage a person.
All this is important to grasp because some people might lead you to believe that you can repair sidewall damage to your tire. Unfortunately, you can’t – it’s illegal and impossible to do it safely.
Why Is This Relevant To Tire Sidewall Damage?
If a tire loses pressure, it can no longer grip the road. Its entire function will become compromised. The wheels will be damaged, along with everything attached to them. You’ll have no grip, and everything will feel all wrong.
Sidewall damage – when it’s deep enough – is technically a form of puncture. It needs to be addressed just as urgently as any other type.
In fact, even more so. You can’t repair the sidewall (no matter what the Internet would have you believe). Thus, you need to remove the old tire and replace it with a new one.
How Is A Car Tire Built, Structurally?
A modern car tire results from the conscious evolution of rubber and wheels over the last century.
We’ll start at the outside and work our way in. Check out this video.
As I’m sure you’re aware, the tread of the tire is the patterned bit down the center. Its main functions are to grip the road and to expel water. These combine to provide optimal grip in many driving scenarios.
The cap of the tread is the part that’s usually in contact with the road. The shoulder is the “curved” bit at the edge of the tire, connecting it to the sidewall. Underneath the cap, you’ll find the base. The base prevents damage to the internal casing of the tire, called the casing.
Underneath the tread, there are two layers of plies. First, jointless cap plies wrap around the tire completely without overlapping with each other. They allow the vehicle to travel at faster speeds. Then, there’s a layer of steel cord belt plies to provide structure and rigidity.
The interior of the tire is called a casing, body, or carcass (cheery(!)). Around this, you’d find a layer of textile ply acting to protect the tire’s internal pressure. Then there’s the inner liner – the inner tube of tubeless tires – made of butyl rubber. It seals the inner chamber, the bit that fills with air when you pump it up.
The sidewall is part of this structure, protecting the interior of the tire from outside conditions. You could think of the sidewall as the tire’s exterior wall.
Finally, there’s the tire’s bead. The bead is what connects the tire to the wheel. The bead reinforcement and apex make driving smoother and more comfortable, making the driver feel more in control of the car. Then there’s the bead core, which is a steel wire sitting in the rubber. It ensures that the tire firmly grasps the wheel rim.
What Causes Tire Sidewall Damage?
Tire sidewall damage can be caused by curbs, random foreign bodies, or incorrect tracking, or wheel balancing.
When you hit a curb, the tire sidewall can be torn by the impact. The damage could also be underneath the surface, invisible to the naked eye (initially, at least). Sometimes, you might accidentally rub along against the curb while you’re driving. In this case, friction builds up very quickly within the tire and could cause damage in the form of the sidewall’s structure breaking down.
Whether they admit it or not, I’m sure most people have hit the curb while driving at least once.
Now we move onto what I’ve called “random foreign bodies”. By that, I mean any puncture-causing, grief-inducing glass shard, nail, or other general debris.
When you’re driving along, these can tear the tire sidewall, causing damage. This type of debris can often leave a sort of flap when it damages a sidewall. You’ve probably seen it happen before. Whether or not this damage leads to needing a new tire depends on how deep it goes. I’ll explore that in slightly more detail in the next section.
Incorrect tracking or wheel balancing could also lead to damaged tire sidewalls – tracking, in particular. Although you might not think of it straight away, wheel alignment – toe angles, in particular – leads to excessive forces on the sidewalls of tires.
I have seen the damage this can do personally on many occasions. Here’s one such example.
A customer had a new tire one Monday afternoon after the old one developed an irreparable puncture. They didn’t opt for the optional tracking service (which I would always recommend you take) and returned on Friday (the same week) after realizing how poor the alignment was. When we put the car up in the air, we saw catastrophic damage to the medial sidewall of the offside-front tire. There was no tread left. When we removed the tire from the wheel, it was full of what looks like black sand or the styrene-butadiene rubber from astroturf surfaces.
Unfortunately, as a result, they had no other option other than to fit another new tire, just four or five days after we first installed it. Whether you purchase budget or premium tires, that’s double the cost either way.
That’s the tire breaking down. If they’d driven on that wheel much longer, it could’ve blown out. And that’s why it’s so important to look after your tires.
How Can I Inspect My Tire Sidewall For Damage?
So, how damaged is your tire?
If you’ve clicked on this link, perhaps this is one of the most relevant questions to you.
The most obvious thing you might notice is a bubble in the tire’s sidewall. It looks almost as if the tire has a boil that needs popping. You get these from hitting curbs or potholes or from having insufficient air in the tire while driving. A bubble indicates a structural breakdown within the tire’s wall, and, therefore, it’s incredibly hazardous.
To be absolutely sure, I would always recommend taking your car to your local shop. Get a mechanic to inspect the wheel. They shouldn’t have to take it off the car, but they may like to raise it on a ramp and jack it up. That way, they can get a good look at everything that’s going on.
Sometimes, tire sidewalls can pick up surface damage – surface damage only. Frequently, this will be some tear in the tire’s material, leaving a flap. It might not cause a structural breakdown or puncture or be deep enough to reveal the metal wires.
In this case, the tire is still technically safe to drive on.
To see if the damage doesn’t go beyond the tire’s surface, you can use a blunt instrument. Get it into the flap and see if you can see any wires. The moment you see anything, it means the tire is no longer legal or safe.
(Don’t use a sharp instrument as you might tear the tire doing this.)
You could also keep a close eye on the air pressure. If you don’t need your car for a couple of days, fill it up to its recommended PSI level. Come back to check the pressure regularly. If any air is leaking out, there’s likely a serious problem with it.
Personally, if you’re unsure, I feel there’s no real alternative to getting a professional to take a quick look. That’ll give you peace of mind and reassurance in the future.
If you’re in any doubt – or the technician is – it’s worth getting a new tire or a new set of tires.
Here’s a two-minute video showing you what happens when a bubble develops in a tire’s sidewall. And how dangerous it is.
Can I Repair A Tire With Sidewall Damage?
You can’t repair a tire with sidewall damage, I’m afraid.
You might see blogs or YouTube clips that encourage you to. Please don’t believe them. Trying to repair a tire that’s damaged might well endanger your life. So just don’t do it.
This video shows you exactly when mechanics can repair punctures.
If the tire has been structurally compromised, it can’t be repaired. This includes the sidewall.
If you’re working on the tire’s tread and can see any metal wires extruding from the rubber, even if you have to work your way into the material a bit, that also means you can’t repair the tire.
Should I Leave The Tire With The Damaged Sidewall On The Car?
If you or a professional have determined that the tire is unfit to drive on – no.
You should remove the tire and replace it with the spare. If like with many modern cars, your car doesn’t have a spare tire, you should consider calling out a roadside mechanic or using the puncture repair kit/sealant kit that should come included.
If the sidewall damage is considerable, the tire sealant kit won’t work, and you’ll definitely need some other kind of assistance.
The tire isn’t safe to drive on. Whatever you decide to do, remember that. Even spare wheels often have speed limits of no more than 50 mph, at which point they’ll start to become damaged too.
How Much Will A New Tire Cost?
This is quite a difficult question to answer with any certainty, as it depends… well, it depends on which tire you buy.
When I was working as a mechanic, we would generally divide tires up into three categories:
- Budget tires.
- Mid-range tires.
- Premium tires.
Budget tires cost considerably less than premium brands – at least, initially. The trade-off is that they won’t give the same levels of grip on the road and they’ll wear down/break quicker. As you might expect, the build quality often isn’t so high.
Premium tires tend to be the exact opposite: more robust and hard-wearing, but they’ll burrow quite a hole in your wallet.
And mid-range tires? Somewhere in the middle of all that.
Budget tires aren’t necessarily the best in the long run. Neither are premiums or mid-range tires. It’s about balancing the risks and rewards and various other factors.
- How likely are you to develop a puncture? For this, you might like to consider the general quality of the roads you usually drive on and your historical record in terms of tire repair. If you decide that punctures are likely, you should probably go for either a budget range or one that comes with a warranty.
- Are you selling the car soon? If you own a more expensive, businessman-style car, high-quality tires could be a good selling point for the vehicle. By contrast, budget tires may put potential buyers off. Buyers also look for cars with the same tire brand on each wheel, so bear that in mind too.
- What warranties are available? Sometimes, tire companies offer warranties with their products. Usually, that will entail a certain percentage off a new – depending on how much tread is left – if you get an irreparable puncture.
- How long do you need the tire to last? The longer a tire needs to stay on, the more reason to go for a premium brand.
What Is The Bubble In The Tire Sidewall?
Tire sidewalls can develop damage in the form of a bubble. You might have watched the video higher up in this article showing you the dangers when this happens.
But what causes it?
The bubble develops when air leaks from the tire’s inside to the body of the tire. Hard impacts (potholes, curbs, and the like) are often the reason they develop. For one quick instant, the entire weight of the car is focused on one tiny contact area. This leads to the sidewall’s inside pinching, and, in turn, you get a small hole in the inside liner layer.
You can’t repair sidewall bubbles. They’re a direct hazard to you and your vehicle, and you must replace the tire immediately.
Is A Spare Wheel Safe To Drive On?
Spare wheels are safe to drive on. Absolutely.
If they were unsafe, they wouldn’t be installed on so many cars (in particular, older cars).
However, you shouldn’t usually drive spare wheels at anything over 50 mph. There’ll be a speed limit sticker on the wheel, so before you attach it to the car, you should keep that limit in mind.
All too many times, someone puts the spare wheel on and drives at 70 mph down to the tire shop. The simple act of doing this will lead to the tire breaking down structurally. Continuing at this kind of pace could lead to the spare blowing out.
Obviously, that’s something you should avoid at all costs.
How Grippy Are Tires?
The tire “grips” the road. There’s a coefficient of friction between the rubber and the asphalt.
(If you’re mathematically inclined and interested in Contemporary College Physics, Jones and Childers estimated that the coefficient of friction for a patterned tire was 0.7 on a dry road and 0.4 on a wet road.)
If the tire wasn’t grippy enough, driving would be a real safety hazard. You won’t be able to stop in time, the car would be more difficult to control (especially in corners), and it would constantly feel like driving on ice.
By contrast, if the tire has too much grip, the engine will have to work harder to overcome the forces “sticking” it to the ground. It would be like pulling away through a sea of honey.
Damage to the tire will immediately affect this grip as well as the regular operation of the car.
If the sidewall damage to your tire is deep enough, it’s terminal. There’s nothing more you can do other than replace the tire.
Sometimes, you may find that the sidewall has been cut but that the tire itself is still intact and working perfectly fine. In this case, it’s best to get the opinion of a professional that you trust.
The main point to take away? Tires need to be looked after. It’s vital. Imperative. If they’re allowed to reach the state where it’s dangerous to drive, you could put yourself and others at serious risk.
You can’t ever repair damage to a tire sidewall. If anyone tells you that you can, I guarantee they’re wrong. It’s never worth the risk.
I hope you’ve found this article informative. Feel free to leave a comment down below, and thanks for reading!