An outward bulge or bubble in a tyre sidewall can indicate internal structural damage. Stop using the tyre and arrange professional assistance. Do not keep driving to see whether it grows, and do not assume that normal pressure or plenty of tread makes it safe.
If you notice the problem during a journey, stop somewhere safe and follow the vehicle's breakdown guidance. The priority is a safe replacement or recovery arrangement, not a roadside experiment with the damaged tyre.
What an outward bulge can mean
Continental's guide to tyre damage explains that a pronounced external sidewall bulge can indicate broken cords in the tyre's carcass. Impacts such as a kerb or pothole can overload that structure. Continued use increases the risk of tyre failure.
The visible bubble is therefore different from a superficial scuff on the rubber. Its size does not provide a safe mileage allowance. Nor can a photograph establish how long the tyre will hold pressure.
Tell the fitter about any impact you remember, but do not manufacture a cause if you did not notice one. “Found while washing the car” is a useful and honest history.
Bulge or indentation?
An outward protrusion should not be confused with a shallow inward indentation. Michelin's sidewall guidance distinguishes normal indentations associated with the tyre's construction from bubbles that indicate a structural problem and require replacement.
That distinction is not an invitation to approve an unfamiliar mark yourself. If you cannot confidently describe whether it projects outwards or dips inwards, arrange a professional inspection before using the tyre. Lighting and viewing angle can be misleading in a close-up photograph.
What to do while arranging help
Keep the vehicle stationary in a safe location. Explain that you have found a sidewall bulge, identify the affected corner and describe any pressure warning, vibration or impact. Follow the assistance provider's instructions.
If the vehicle has a suitable spare, its use depends on a safe location, the correct equipment and the handbook procedure. Do not attempt a change beside live traffic or on unstable ground. A temporary spare also has its own operating restrictions; fitting it does not restore unrestricted normal use.
Do not try to push the bulge back, puncture it, heat it or hide it with a sidewall treatment. Reducing pressure is not a repair. A sealant kit intended for certain tread punctures does not rebuild damaged sidewall reinforcement.
Plan the replacement properly
Have the damaged tyre assessed and replaced as required. Michelin's UK sidewall guide treats serious sidewall damage differently from a potentially repairable tread puncture. The question is not simply whether the tyre still holds air.
Before ordering, record the complete tyre size and service description, including load and speed ratings. Ask the fitter about matching the tyres on the axle and any vehicle-specific requirements, particularly for four-wheel-drive systems or staggered fitments.
If an impact preceded the bulge, ask whether the wheel and surrounding components also require inspection. A new tyre should not be fitted to an unassessed damaged wheel. Our buckled-wheel guide explains why appearance and balancing alone cannot establish that a wheel is straight.
Keep a useful record
Photograph the affected sidewall, the complete tyre identification and the wheel before replacement if it is safe to do so. Keep any inspection findings and the invoice. If you wish to raise a tyre warranty enquiry, ask the seller about its assessment process and whether the removed tyre must be retained.
Do not assume that a photograph proves a manufacturing defect or an impact. A proper assessment should establish the evidence; the sales or warranty process then determines the available remedy.
For a replacement-wheel enquiry, send Wheel City the vehicle and wheel details. A tyre bulge alone does not mean that the alloy wheel must also be replaced, but any associated wheel damage needs its own assessment.
Frequently asked questions
Can I drive a short distance with a small tyre bulge?
Do not use the size of the bulge or distance to justify driving. Stop using the tyre and arrange assistance or a safe, suitable spare-wheel change.
Can a bulge disappear after cooling down?
Do not treat a change in appearance as proof that the structure has recovered. Have the tyre assessed and explain what you previously observed.
Does good tread depth mean it is safe?
No. Tread depth and structural condition are separate checks. A tyre with substantial remaining tread can still be unsafe because of sidewall damage.