A puncture does not automatically mean a new tyre, but nor can every puncture be repaired. In the UK, tyre repairs follow British Standard BS AU 159, and a repair is only safe and legal if it meets all of its conditions. Miss any one of them and the tyre must be replaced.
The conditions for a legal repair
Every one of these must hold:
- Location: the damage must be in the central three-quarters of the tread, the area that contacts the road. Damage in the shoulder or sidewall cannot be repaired.
- Size: the puncture hole must be no more than 6mm in diameter. Larger penetrations disturb too much of the internal structure.
- Not driven flat: the tyre must not have been run flat or badly under-inflated, which causes hidden internal damage.
- No structural damage: no exposed or broken cords, no splits or cracks reaching the casing, no bead damage or contamination.
- Legal tread: the tyre must not already be worn below the 1.6mm limit.
- Proper method: the tyre must be removed from the wheel, inspected inside and out, and repaired with a combination plug-and-patch.
If a fitter offers to plug a tyre without taking it off the wheel, that is not a compliant repair.
A proper repair is a full repair
A common worry is that a repaired tyre is somehow second-rate. It is not. A tyre repaired correctly to the standard keeps its original speed and load ratings and can be driven normally. The repair restores the tyre rather than downgrading it.
On how many repairs a tyre may have, the standard sets no fixed number, as long as repairs do not overlap and the tyre is otherwise sound. Some tyre makers and fitters are stricter with high-speed tyres, those rated V and above are sometimes limited to a single repair, so it is sensible to ask when the tyre is a performance one.
What does not count as a repair
Several quick fixes are emergency measures only, not permanent repairs:
- Liquid sealant or foam poured or injected into the tyre
- External plugs pushed in without removing the tyre
- Inner tubes fitted inside a tubeless tyre
These can get a car to a garage, but the tyre still needs a proper inspection and a compliant repair, or replacement, at a proper fitter, the kind of inspection a service like Tyres.co.uk arranges through its fitting network.
When the answer is replacement
If the damage is in the wrong place, too large, structural, or the tyre has been driven flat, no safe repair is possible and the tyre must be replaced. The detail of which damage falls where is covered in the guides on the repair area and on a tyre that is beyond repair. Run-flats are a special case, since a run-flat driven on after a puncture usually cannot be repaired at all. And where a repair looks possible but a garage still declines it, the reasons a fitter turns a repair down explain what they have spotted.
From the workshop: the question I am asked most is "can you just plug it?" If it is a nail in the middle of the tread and the tyre has not been driven flat, almost certainly yes, properly, off the rim. If it is in the shoulder, the answer is no, and no amount of asking changes the standard.
Sources and accuracy. The BS AU 159 conditions and the ratings and repair-count points here reflect the British Standard and industry guidance at the time of writing, which can change. Anything safety-critical should be confirmed against the current standard and a qualified fitter. If anything here looks wrong, get in touch and we will check it and put it right.
Common questions
Can a punctured tyre always be repaired?+
No. A repair is only safe and legal if it meets every condition of British Standard BS AU 159: the damage must be in the central tread, under 6mm, the tyre must not have been driven flat, there must be no structural damage, and it must be a proper combination plug-and-patch after the tyre is removed and inspected.
Does a repaired tyre have to be replaced sooner?+
No. A tyre repaired correctly to BS AU 159 keeps its original speed and load ratings and can be used normally. The repair is only a problem if it was done outside the standard, for example an external plug or a sidewall repair.
How many times can a tyre be repaired?+
There is no fixed limit under the standard, provided repairs do not overlap and the tyre is otherwise sound. Some manufacturers and fitters apply a stricter limit on high-speed tyres rated V and above, often a single repair, so it is worth asking.
Is a tyre sealant or foam a proper repair?+
No. Sealant foams and external plug kits are emergency, get-you-home measures only. They are not recognised as permanent repairs under BS AU 159, so the tyre still needs a proper inspection and repair, or replacement, afterwards.