If finding a bubble in your tire’s sidewall has led you to this blog article, then there’s a good chance you are looking for answers to several questions:
- What causes a sidewall bubble?
- What is the impact of a sidewall bubble?
- Should the tire be repaired, or replaced?
We hope that the following information will help.
What causes sidewall bubbles in tires?
The underlying cause of a tire bubble formation is the separation of layers of material – plies and rubber – in the sidewall of a tire. You may already know that a tire is constructed by layering hundreds of polyester cords or other strong materials (also known as plies) with layers of rubber, sometime cemented together by bonding materials like glue. The rubber layers hold the air in the tire while the plies provide structure, shape, and strength to the tire under pressure. Since the durability of a tire is dependent upon the bonding strength between these component layers, a loss of bonding strength can lead to ply or layer separation. Loss of bonding strength and separation can be caused by several factors, among which are:
- Contamination of components or other defects during manufacturing (a rare occurrence)
- Under inflation or over loading of the tire (more common – depends on the driver)
- Tire damage caused by road hazards such as striking the curb or hitting a pothole (most common – often the driver is unaware of the incident)
When a layer separates due to one of these factors, air can permeate through one or more internal layers, migrate toward the outside of the tire, and collect under the outer plies (layers) of the tire. As a result, the outer rubber layer in the area of the internal damage may bulge or bubble. This is always a sign that pressurized air from the inside of the tire is migrating through the internal tire structure and is trying to escape.
What is the impact of a tire sidewall bubble?
Since it is always a sign of internal failure, continued use of the bubbled tire can lead to continued gradual weakening of the over-strained cords which can cause a larger bulge and eventually cause the tire to fail, perhaps catastrophically. A weakened tire is much less able to handle road hazards like potholes.
What should you do if you have a sidewall bubble?
Any tire that develops a bubble (in the sidewall or the tread) is not repairable. The internal structure has failed and the tire itself is very likely to fail at some point. The tire bubble may grow or get larger over time as the air pressure continues to delaminate the inner plies. Or, the tire can suddenly fail catastrophically. While the pressure may hold for some time without the tire failing, continued driving, driving at high-speed, or more impacts to the tire like speed bumps or potholes will continue to worsen the problem leading to eventual failure. Bottom line, continuing to use the tire is a risk you should avoid.
If your tire has developed a bulge, you should have it inspected and replaced as soon as possible by a reputable tire dealer. You should not continue to drive the vehicle as your safety is at risk. Many people think a tire bubble is usually caused by a manufacturing defect. If your tire experiences a sidewall bubble from a defect, all reputable tire manufacturer’s warranties will cover replacement. However, it is extremely unlikely that a defect caused a bubble and 98%+ of the time, a reputable dealer will be able to point out to you evidence of damage to the tire caused by a road hazard. Road hazards are rarely covered under standard manufacturer warranty policies.
However, road hazard insurance bought when you buy new tires will cover all, or some, of the cost of replacing a tire that has a sidewall bubble caused by road hazard damage; check the paperwork that came with your policy for the specifics of your coverage. When buying road hazard insurance, make sure you understand any limitations of the policy that might restrict coverage.
At AutoSquad, we always appreciate your feedback and try our best to respond promptly to any questions. So, please free to share your thoughts on this article, or ask us questions you may have on this or other topics.