Tyre bulge: everything you need to know to act fast

A tyre bulge is a visible issue affecting the tyre’s structure. It appears as a bump on the sidewall.

A bulge weakens the tyre and increases the risk of a blow-out. It is therefore essential to act at the first signs so as not to compromise the safety of the driver and passengers.

How to recognise a bulge, what causes it, the risks involved and, above all, the right steps to take.

What is a tyre bulge and how do you identify it?

A bulge is a visible deformation on the tyre sidewall, usually in the form of a bump that can vary in size. It appears when the tyre’s metal structure is damaged.

Unlike a puncture, a bulge indicates an internal structural failure of the tyre that is visible to the naked eye.

A tyre is made up of several superimposed layers:

• The rubber, also called the tread, which provides grip and resists wear.
• The fabric plies, which add flexibility and reinforce the internal structure.
• The metal belts that give the tyre its strength and allow it to support the vehicle’s weight.

During an impact, the tyre’s inner protective layers can give way, allowing the internal pressure to create a bulge at the most vulnerable point.

Clear visual signs:

• Visible bump on the tyre sidewall
• Asymmetrical or unusual deformation

Indirect signs to watch for:

• Unusual vibrations in the steering wheel, especially at high speed
• Abnormal noises in a straight line or when cornering

Never ignore an unusual, visible deformation on your tyre, even if it seems minor. Stop driving as soon as possible and replace the tyre.

What causes a tyre bulge?

• Impacts and shocks: Heavy impacts against kerbs, edges or potholes at high speed can cause a bulge.
• Excessive stress: Overloading the vehicle, under-inflating or over-inflating the tyres can weaken the structure and increase the risk of a bulge.
• Manufacturing defects: Certain manufacturing faults, such as uneven rubber distribution or defective belts, can also be responsible.

Can a tyre bulge be repaired?

No. A bulge is an irreversible structural failure. The tyre’s internal structure is damaged and cannot be repaired.

Attempting to repair a bulge is dangerous and can lead to a blow-out. The tyre must be replaced.

What are the dangers of driving with a bulging tyre?

Driving with a bulging tyre is hazardous, as the tyre can burst suddenly, especially at high speed, which may result in loss of control of the vehicle.

Bulge vs puncture: what’s the difference?

A bulge is structural damage to the tyre, whereas a puncture is generally superficial and can often be repaired.

How much does it cost to replace a tyre with a bulge?

The price of a new tyre depends on size, brand, vehicle type and required performance (summer, winter, all-season, run-flat, etc.). Find the right tyre for your vehicle.

Practical tips to avoid a tyre bulge

To prevent a bulge from forming, avoid impacts with kerbs and edges. Do not overload the vehicle, as this can cause a bulge.

It is recommended to check tyre pressure and visually inspect the tyres at least once a month to spot any faults or bumps.

A bulge is a serious internal deformation that may appear as a bump. It makes the tyre unstable and dangerous. Replace the tyre as soon as the first signs are detected.

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