The quick answer
An outward bulge, exposed cords or suspected structural damage needs urgent professional attention. Do not keep driving to see whether it changes. A superficial scuff may be less serious, but a photograph cannot reliably establish the depth or internal condition.
Recognise an outward bulge
A bubble standing outward from the sidewall can indicate damaged reinforcement inside the tyre, including after an impact with a kerb or pothole. A tyre can still hold air while structurally damaged. Michelin explains the significance of sidewall bulges. Arrange professional assistance before continuing the journey.
A slight inward indentation can be associated with normal radial tyre construction and is different from an outward bulge. Do not try to identify a questionable shape solely by comparing it with an internet image; have a competent specialist assess it.
Do not assess a cut by length alone
A short cut may be deep, while a longer superficial scrape may only involve surface rubber. Look for what is visible without touching: rubber lifting away, reinforcement showing, or damage accompanied by deflation. Do not prise open the cut or insert a tool to inspect it yourself.
Tell the professional whether the tyre hit a sharp object, kerb or pothole and whether you drove afterwards. Damage on the inner sidewall can be harder to see; a clean-looking outer side is not a full inspection.
Understand scuffs and cracking
Minor cosmetic marks do not all mean a tyre is condemned. Their seriousness depends on depth, location and condition. Cracks are also a reason to seek assessment, particularly where there is evidence of deterioration rather than a light surface mark.
A tyre’s tread depth is only one part of its condition. Having ample tread does not cancel out a structural defect. Equally, age or a photograph alone cannot provide a complete diagnosis of an individual tyre.
What a photograph can and cannot tell you
| A photograph may help show | It cannot reliably establish |
|---|---|
| A visible bulge, cut or exposed material. | The full internal condition of the casing. |
| Tyre markings and the affected wheel. | Whether all fitment requirements are met. |
| A safe parking position or access restriction. | That the vehicle is safe to drive. |
Photograph only what can be reached safely. If you are at the roadside, personal safety comes before collecting evidence. Do not stand on the traffic side of the vehicle to obtain a picture.
Repairability is a separate assessment
Structural sidewall damage is not covered by the routine minor puncture-repair process for cars and light vans. Repair decisions require a trained person to assess the tyre, including internally where appropriate. See how puncture repairability is assessed.
Fix My Tyre offers replacement, not puncture repair. If replacement is needed, call with the location, registration and tyre markings if safely available. Also disclose any suspected wheel damage; fitting a new tyre does not automatically solve a damaged rim.
A practical next-step checklist
- Keep a tyre with an outward bulge or exposed reinforcement out of service pending professional advice.
- Record the impact or symptoms you noticed and any subsequent driving.
- Get the exact vehicle and tyre details ready without risking your safety.
- Arrange suitable assessment, replacement or recovery as the position requires.
Do not plan around “it has not gone down yet”. Air retention does not prove the reinforcement is intact.
Common questions
Will a bulge disappear if I let some air out?
Changing the pressure does not restore damaged reinforcement. Do not try to treat a bulge by adjusting the tyre pressure.
Is every small sidewall mark a replacement?
No. Some marks are superficial. A competent assessment is needed where severity is uncertain; visible structural damage is a different matter.
Can I wait until my MOT to deal with it?
An MOT date is not a reason to continue using a tyre with a suspected dangerous defect. Arrange assessment now.
Sources and further reading
Guidance checked on 10 October 2026. Use the current official instructions for your vehicle and circumstances.