Can a puncture be repaired, or do you need a new tyre?

The short answer A car tyre puncture can normally be repaired if the damage is in the central three-quarters of the tread, is no more than about 6mm across, and the tyre has not been driven on while flat. Sidewall and shoulder damage is never repairable.

The repairable area

Picture the tread split across its width into four strips. The outer strip on each side — the shoulders — is off limits. Only the middle section can take a repair, because that is the part of the tyre that stays flat against the road and is backed by the full casing structure.

Move outwards into the shoulder and the rubber is flexing constantly as the tyre rolls and corners. A plug there works loose. That is why a reputable fitter will refuse a repair that a tyre-sealant advert implies is fine.

Damage that can never be repaired

• Sidewall damage of any kind. Cuts, splits or a nail through the side. The sidewall does the flexing, and there is no way to patch it that survives. See sidewall damage and bulges.
• A bulge or egg. This means the internal cords have already snapped, usually from a pothole or kerb. The tyre is structurally finished even though it is holding air.
• Anything driven on while flat. Running a deflated tyre grinds the inner liner to dust within a few hundred yards. It may look fine from outside and be scrap inside — can you drive with a puncture?
• A tyre already at or near the legal limit. Repairing a tyre with 2mm left is money you will spend again in a month — tread depth and the UK legal limit.
• Multiple repairs close together, or a second repair overlapping an existing one.
• Most run-flat tyres that have been driven on deflated — run-flat tyres explained.

What a proper repair involves

A correct repair is done from the inside. The tyre comes off the rim so the fitter can inspect the inner liner — which is the only way to see whether the casing has been damaged. The hole is prepared and sealed with a combined plug and patch, then the wheel is rebalanced.

An external plug pushed in without removing the tyre is a roadside get-you-home measure, not a repair. If someone offers that as a permanent fix, be sceptical.

There is a standard behind this Tyre repairs for road vehicles in the UK are governed by British Standard BS AU 159 — "specification for repairs to tyres for motor vehicles used on the public highway". The repairable-area and size limits above are not one fitter's preference; they come from that standard, and the same document is referenced in the regulations covering the sale of part-worn tyres.

Step by step, so you know what you are paying for

1. Wheel removed from the vehicle.
2. Tyre removed from the rim — non-negotiable for a proper assessment.
3. Internal inspection of the liner and casing for hidden damage.
4. Injury cleaned and prepared to the correct diameter.
5. Combined plug-and-patch unit fitted from the inside and sealed.
6. Tyre refitted, new valve where appropriate, and the wheel rebalanced.
7. Pressures set and bolts torqued to the manufacturer's figure.

If any of steps 2, 3 or 6 are missing, what you have had is not a repair to standard.

Why we will sometimes tell you it is repairable

It is worth saying plainly: a repair is cheaper for you and less profitable for us. If we say a tyre needs replacing, it is because of where the damage is, not because we would rather sell you a tyre. Ask us to show you — the position of the damage is visible and you can judge it yourself.

What about sealant kits?

The aerosol kits supplied in place of a spare will get a small tread puncture holding air long enough to reach somewhere safe. They are a mobility aid. The tyre still has to be inspected and usually replaced afterwards, and the sealant has to be cleaned out of the rim and the valve.

Always tell the fitter that sealant has been used. See space-saver or sealant kit and flat tyre with no spare.

Common questions

How many times can one tyre be repaired?

There is no single number, but repairs must not overlap or sit close together, and each one reduces what remains repairable. A tyre with several existing repairs will often be refused.

Is a repaired tyre as good as new?

A repair carried out to BS AU 159 in the correct area restores the tyre for normal use. Some tyres are speed-marked after repair; the fitter should tell you if that applies.

The nail is still in and holding air. Do I need to do anything?

Yes — get it looked at, but leave the nail in place until then. Pulling it out turns a slow leak into a flat. See why a tyre keeps losing pressure.

Can you repair it at my house?

Yes — a properly equipped van can take the tyre off the rim, inspect it, repair it and rebalance the wheel on your driveway. See what is mobile tyre fitting.

My tyre keeps going down but there is nothing in it.

Often a corroded rim seat or a failing valve rather than a puncture. Both are fixable, and both need the tyre off the wheel.

Not sure which you have?

Send us a photo of the damage before we come out and we will usually be able to tell you over the phone. Call 07989 606060, or read more about our mobile puncture repair service.