A Tire Sidewall Bubble Means You Need a Replacement Soon
A sidewall bubble means the tire is failing and needs to be replaced
A sidewall bubble — a bulge on the side of your tire — is a sign that the inner structure of the tire has been damaged. The bubble forms when air pressure pushes against a weak spot in the rubber and fabric layers underneath. This is not a repair situation. You cannot patch a sidewall bubble, and driving on it risks a blowout, which can cause you to lose control of your vehicle.
The bubble will only grow larger as you drive. Even if it looks small right now, the damage is already significant enough that the tire cannot safely hold pressure. You should stop driving the vehicle except to get to a tire shop, and you should not take the highway to get there.
How you replace the tire depends on whether you have a spare, whether your vehicle is all-wheel drive, and whether the other tires are worn. Understanding these factors will help you make the right choice and avoid spending more than necessary.
Key Takeaways
- A sidewall bubble cannot be repaired and the tire must be replaced before you drive the vehicle on the highway or at high speed.
- If you have a full-size spare, you can drive to a tire shop on it, but check that it has air pressure and is not also damaged.
- On all-wheel-drive vehicles, replacing only one tire can damage the transmission and differential, so you may need to replace two or four tires instead of one.
- If the other tires are worn, replacing just the damaged tire now and the rest later can cost more overall than replacing all four at once.
- A tire shop can tell you in minutes whether you need one replacement or more, and what your options cost.
Why the sidewall is different from the tread
The tread — the grooves on top of the tire — can be patched because it is designed to wear. The sidewall is not. It is a thinner, more flexible part of the tire that holds the tire's shape and keeps air sealed inside. When the sidewall is damaged, the tire loses structural integrity.
A sidewall bubble happens when the fabric and rubber layers separate or tear. This can occur from hitting a pothole, curb, or road debris hard enough to damage the side of the tire. It can also happen if the tire was underinflated for a long time, which puts extra stress on the sidewall. Once the damage starts, air pressure makes the bubble grow.
Driving on a tire with a sidewall bubble is dangerous because the bubble is a weak point where the tire can suddenly fail. A blowout at highway speed can cause you to lose steering control or jackknife a trailer.
What to do right now
First, check your spare tire. Open your trunk or look under your vehicle to see what spare you have. If you have a full-size spare (the same size as your other tires), check that it has air in it by pressing on it with your thumb — it should feel firm, not soft. If you have a donut spare (a small temporary tire), it is meant only for short distances at low speed.
If your spare is usable, you can change the tire yourself if you know how, or you can call a roadside service to change it for you. If you do not have a spare or it is flat, call a tow truck to take your vehicle to a tire shop. Do not drive on the highway with a sidewall bubble, even slowly.
Once you reach a tire shop, tell them you have a sidewall bubble and ask them to inspect the tire and check the condition of the other three. They will tell you whether you need one replacement or more, and they can show you the options and prices.
One tire or more than one: what it depends on
On a front-wheel-drive or rear-wheel-drive vehicle, you can usually replace just the one damaged tire if the other three are in decent condition. "Decent condition" means the tread is not bald and the tires are the same brand and type. The tire shop can measure the tread depth to confirm.
On an all-wheel-drive vehicle, the rules are stricter. All four tires need to be nearly the same size and tread depth, because the vehicle's computer monitors each wheel's speed. If one tire is significantly newer or smaller than the others, the transmission and differential can be damaged by the mismatch. Some all-wheel-drive vehicles require all four tires to be replaced together. Others allow you to replace two (both front or both rear) if the other two are close in tread depth. Ask the tire shop what your vehicle's manual says, or they can look it up.
If the other three tires are worn and close to needing replacement anyway, it often costs less to replace all four now than to replace one now and three later. The tire shop can show you the math.
Choosing between a new tire and a used tire
A new tire from a tire shop comes with a warranty and is may provide to have no hidden damage. A used tire from a salvage yard or online marketplace is cheaper but carries risk — you cannot see internal damage, and you have no recourse if it fails.
If you are replacing one tire on a vehicle with low mileage and good tires, a new tire is the straightforward choice. If you are replacing multiple tires or the other tires are already old, you might consider a used tire for the damaged wheel and plan to replace all four within a year or two. A tire shop can advise you on whether a used tire is safe for your situation.
Some tire shops also sell refurbished tires, which are used tires that have been inspected, repaired, and retested. These are cheaper than new but more reliable than random used tires.
What to expect at the tire shop
Bring your vehicle keys and be prepared to wait 30 minutes to an hour while the tire is changed and balanced. The shop will remove the damaged tire, mount a new one on the rim, and use a machine to balance it so it does not vibrate at highway speed. Balancing costs extra — usually between $15 and $25 per tire — but it is necessary.
Ask the shop to show you the damaged tire so you can see the bubble. This helps you understand what happened and what to watch for on your other tires. If the bubble is on a tire that is less than a year old, ask whether the tire came with a warranty that might cover the damage. Some manufacturers cover sidewall damage if it was a manufacturing defect rather than road damage, though this is rare.
Before you leave, ask the shop to check your tire pressure and set it to the correct PSI for your vehicle. You can find the correct pressure on a sticker inside the driver's door or in your owner's manual. Underinflated tires wear faster and are more prone to sidewall damage, so keeping them at the right pressure helps prevent this problem in the future.
How to avoid sidewall bubbles
Check your tire pressure once a month and before long trips. Underinflated tires are more likely to develop sidewall damage. You can find the correct pressure on the sticker inside your driver's door — not on the tire itself, which shows the maximum pressure.
Avoid potholes and debris when you can, and drive carefully over rough roads. If you hit something hard, pull over safely and inspect your tires for bulges, cracks, or cuts. Catching damage early can sometimes prevent a blowout.
Rotate your tires every 5,000 to 7,000 miles. Rotation helps tires wear evenly and extends their life, which means you are less likely to have one tire fail while the others are still good.
Frequently Asked Questions
Can I drive to the tire shop if the bubble is small?
No. Even a small bubble means the tire's structure is compromised. Drive only to the nearest tire shop, and use back roads rather than the highway. If the shop is far away, call a tow truck instead.
What if I hit a pothole and now my tire looks flat but I do not see a bubble?
The tire may have a slow leak from a puncture in the tread, or the impact may have damaged the sidewall in a way that is not yet visible. Pull over safely and inspect the tire closely. If you see any bulge, cut, or crack, do not drive it. If the tire just looks flat, it may have lost air pressure. Add air at a gas station and monitor it. If it loses air again within a day, there is a leak and the tire needs to be inspected by a shop.
Do I have to replace all four tires if one has a sidewall bubble?
Not always. On front-wheel-drive and rear-wheel-drive vehicles, you can replace just the damaged tire if the others are in good condition. On all-wheel-drive vehicles, you may need to replace two or four depending on the tread depth of the other tires. The tire shop will tell you what your vehicle requires.
How much does a tire replacement cost?
A new tire costs between $50 and $300 depending on the size and quality. Labor and balancing add another $30 to $50. A used tire costs less but carries more risk. Ask the shop for a quote before they start work.
What if the tire shop says the damage is a manufacturing defect?
Some tire warranties cover manufacturing defects, which are rare. The shop can help you file a claim with the tire manufacturer. This process takes weeks and is not may provide, so ask whether the shop can replace the tire now and you can pursue the warranty claim separately.