Punctured run-flat: what to do

How does a run-flat behave when it's punctured?

A punctured run-flat keeps supporting the car thanks to its reinforced sidewalls, so from the outside it looks almost normal and the car drives much the same. That's exactly why the first, and often only, sign is the tyre pressure warning light: run-flat tyres require a TPMS precisely because otherwise a puncture could go unnoticed.

How they work is explained in the guide run-flat tyres: how they work.

How far can you drive on a punctured run-flat?

On a punctured run-flat you can drive a limited distance at reduced speed: many manufacturers state, as a guide, up to around 80 km at a maximum of 80 km/h. The actual figures depend on the tyre, the vehicle and the load, so always check the owner's manual and the tyre manufacturer's guidance.

• The more heavily loaded the car, the shorter the usable distance.
• Avoid sharp braking, fast cornering and potholes.
• If you feel vibrations, hear noises or see smoke, stop immediately.

In the city, in Milan, distances are short, but it's still best to stop somewhere safe and have the tyre checked, rather than carrying on with your day as if nothing had happened.

What should you do when the warning light comes on with run-flats?

1. Reduce your speed gradually without braking sharply.
2. If you can, check on the display which wheel has lost pressure.
3. Get to a safe spot, staying within the distance and speed limits indicated.
4. Stop, switch on your hazard lights and visually check the tyre: look for nails, cuts or sidewall damage.
5. Don't use sealant unless the manufacturer allows it.
6. Photograph the tyre and note down the size and the run-flat marking on the sidewall.
7. Call for assistance to have the tyre assessed.

Can a punctured run-flat be repaired?

A run-flat can only be repaired in limited cases, and many manufacturers advise against it or allow it only under specific conditions. The reason is that, when driven without pressure, the reinforced sidewall can suffer internal damage that isn't visible from the outside.

The technician must remove the tyre, inspect it inside and check the manufacturer's guidance: if the tyre has been driven a long way deflated or there are signs of internal damage, it must be replaced. For the general criteria, read when a tyre can be repaired.

What's different for the tyre fitter with run-flats?

Run-flats have stiff sidewalls and require suitable equipment and procedures for removal and fitting, so as not to damage the tyre, the rim or the pressure sensor. That's why it helps to tell us straight away on the phone that they're run-flats.

Also, cars with run-flats often have no spare wheel: if the tyre can't be repaired, a replacement needs to be checked on the phone based on size and availability. See also no spare wheel.

How does SOS Tyre deal with a punctured run-flat?

SOS Tyre comes out 24/7 to wherever you've stopped, in Milan and its province, with a very fast response: on the street, outside your home, at the office or in a garage. Call +39 377 326 0999 or fill in the assistance request and tell us:

• the location of the vehicle;
• make and model, specifying that it has run-flats;
• the full tyre size, read from the sidewall;
• how many kilometres you've driven since the warning light came on, plus a photo of the tyre.

The technician assesses whether an on-the-spot repair is possible according to the manufacturer's guidance.