Can you drive on a punctured tyre?

What happens if you drive on a flat tyre?

If you drive on a flat tyre, the sidewall is squashed and flexed with every turn of the wheel. This overheats and breaks the internal structure, even if the damage isn't visible from the outside straight away.

• Tyre: the internal plies are damaged and a tyre that might have been repairable has to be replaced.
• Wheel rim: without air the rim can touch the tarmac or kerbs and get scratched, bent or cracked.
• Handling: the car tends to pull to one side, responds less well to steering and brakes less effectively.

Are a punctured tyre and a flat tyre the same thing?

No. A punctured tyre has a hole but may still hold some air; a flat tyre is completely or almost completely deflated.

With a small puncture (for example a nail still embedded) the air loss can be slow. In this case the pressure warning light may come on before you notice anything. Even a tyre that's losing air slowly shouldn't be used for normal journeys, though: the pressure drops as you drive and the risk of it going completely flat increases. Find out more on the page about a deflated tyre.

When is it acceptable to move a few metres?

Moving a few metres is acceptable when staying put is more dangerous than moving, for example if you're in the middle of a junction, on a bend or in a live traffic lane.

1. Switch on your hazard lights.
2. Drive at walking pace, without sudden braking or steering.
3. Get to the first safe spot: a lay-by, a car park, the edge of the road away from traffic.
4. Stop, switch off the engine and make yourself and your passengers safe.

The aim isn't to "make it to the tyre shop" but to get out of danger. For the rules on warning triangles and high-visibility vests, read how to stay safe after a puncture.

What if I have run-flat tyres?

With run-flat tyres you can carry on after losing pressure, but only for a limited distance and at reduced speed. Many manufacturers give, as a rough guide, up to about 80 km at a maximum of 80 km/h, but the correct figures are those in the vehicle handbook and from the tyre manufacturer.

Even with a run-flat, driving without pressure stresses the structure: afterwards, the tyre must be checked. Find out more in run-flat tyres: how they work.

Can you use a repair kit and carry on?

Yes, but only if the hole is small and in the tread. A sealant-and-compressor kit doesn't work on cuts or shoulder damage, and it's only a temporary fix.

After using the kit you must follow the instructions printed on it (usually moderate speed and limited distance) and have the tyre checked by a tyre specialist. The comparison with a space-saver is in repair kit or space-saver.

How can you tell whether the tyre can still be repaired?

You can only partly tell from the outside: a definitive assessment requires the tyre to be removed and inspected on the inside too. In general, the longer you've driven on it flat, the lower the chances of a repair.

Signs that suggest a tyre needs replacing: damage on the shoulder, long cuts, bulges, visible plies, rolling marks on the sidewall. You'll find the criteria in when can a tyre be repaired.

If you're stuck in Milan with a punctured tyre

If you're in Milan or the surrounding province and don't want to risk ruining the tyre and wheel rim, you can stay safely where you are and ask for an on-the-spot call-out. SOS Tyre operates 24/7, with an average arrival time of 30 minutes: on the phone we tell you what's feasible and when we'll arrive. Call +39 377 326 0999 or use the assistance request.