Run-flat tyres are designed to keep going after a puncture, which is exactly why they are usually replaced rather than repaired. The same feature that gets a car home is what makes a reliable repair impossible to guarantee.
How run-flats work
A run-flat has a reinforced sidewall strong enough to support the weight of the car even with no air in the tyre. After a puncture, that lets the driver carry on for a limited distance, typically up to around 50 miles at up to 50mph, depending on the make, rather than stopping at the roadside. There is more on identifying them in the guide to run-flat markings.
That capability is meant for reaching a fitter safely, not for carrying on indefinitely.
Why repair is usually ruled out
The catch is what happens while the tyre runs deflated. Supporting the car with no air generates heat in the reinforced sidewall, and that heat can damage the internal structure. Crucially, the damage is not visible from the outside, the tyre can look fine while being compromised inside.
Because that damage cannot be confirmed by inspection, the British Standard does not approve repairing a tyre that has been driven flat. And since a run-flat puncture is almost always discovered after some driving, the practical result is that most run-flats are replaced, ideally with a like-for-like run-flat, which a search by size on the tyre site Tyres.co.uk will turn up. Most car makers and tyre manufacturers advise against repairing run-flats for the same reason; a few permit it only under strict conditions, but the industry default is replacement.
The cost trade-off
This is the hidden running cost of run-flats. On a standard tyre, a nail in the tread is often a low-cost repair. On a run-flat, the same puncture usually means a new tyre, which costs considerably more. It is one of the trade-offs that comes with the convenience of being able to drive on after a puncture.
For drivers whose cars came on run-flats, it is worth knowing this in advance, so a puncture is less of a surprise, and worth checking whether the car is suitable for standard tyres if the run-flat premium is unwelcome.
From the workshop: nine times out of ten, by the time a run-flat reaches me it has already been driven on flat, even if only a few miles. I cannot see inside the sidewall to know what that heat has done, and I will not gamble on it. That is why it is a replacement, not a repair.
Sources and accuracy. The run-flat design figures and the repair position here reflect manufacturer and industry guidance at the time of writing, which can change and varies by make. Anything safety-critical should be confirmed against the tyre maker's guidance 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 run-flat tyre be repaired after a puncture?+
Usually not. Most manufacturers and fitters advise against it, because driving on a run-flat while deflated, even within its limits, can heat-damage the reinforced sidewall in a way that is not visible from outside. The standard does not approve repairing a tyre that has been run flat.
Why are run-flats treated differently?+
Their reinforced sidewalls let the car keep going after a puncture, but supporting the weight while deflated generates heat that can weaken the structure. Because the damage cannot be confirmed by inspection, replacement is the safe default.
How far can you drive on a run-flat after a puncture?+
Typically up to around 50 miles at up to 50mph, though the exact figure depends on the make. That capability is for getting to a fitter, and because the tyre is usually driven on after the puncture, it normally needs replacing rather than repairing.
Are run-flats more expensive to own?+
Often, yes. A puncture that would be a low-cost repair on a standard tyre usually means buying a new run-flat, which costs considerably more. It is one of the trade-offs of the run-flat design.