Tyre punctures and repairs: the answers | Pneumatici SuperStore

Question 1

When can a punctured tyre be repaired?

Accepted Answer

Only if the damage is in the central area of the tread, is small and the tyre has been demounted and inspected on the inside. Continental indicates as repairable the central part for about three quarters of the tread (the 'minor repair area'), and as not repairable any hole of 6 mm or more. Sidewall, shoulder, cuts, visible cords and tyres damaged by driving at low pressure are excluded.

Question 2

Why can a tyre sidewall never be repaired?

Accepted Answer

Because the sidewall flexes continuously while driving and has a thin structure that does not support a reliable repair: a patch there risks failing. Continental says it clearly: a puncture outside the repair area, in the sidewall or close to it, is not repairable. Tyres with shoulder damage or with the inner bead visible must also be replaced.

Question 3

Is a plug or 'mushroom' enough to repair a puncture?

Accepted Answer

No. Michelin states that plug-only repairs done without removing the tyre from the rim are improper and can cause accidents. The correct repair involves demounting the tyre, inspecting the inside and applying a combined plug plus internal patch system (patch-plug). A plug applied from the outside can serve at most as an emergency solution to reach the tyre shop, not as a permanent repair.

Question 4

Why must the repair be done from the inside of the tyre?

Accepted Answer

Because only by demounting the tyre can you see whether the damage has affected the internal structure: Michelin states that the tyre must be removed from the rim and inspected, because some damage cannot be seen from the outside. Continental warns that driving on a flat tyre makes the sidewall work against the rim and extends the damage beyond the repairable area. That is why it is not worth continuing for long on a flat tyre.

Question 5

Can I repair the same tyre more than once?

Accepted Answer

It depends on the manufacturer, the position of the damage and the condition of the tyre: there is no figure valid for everyone. Continental excludes repair if there are signs of previous poorly done repairs. For its own run-flats, Michelin states they can be repaired only once by a professional, except those marked as not repairable on the sidewall. The tyre fitter assesses case by case after demounting and inspecting the tyre.

Question 6

Do you repair punctures at Pneumatici SuperStore?

Accepted Answer

Yes, puncture repair is among the services of the Pneumatici SuperStore centre in Milan. A correct repair requires demounting the tyre and inspecting it on the inside: if the damage is not in the repairable area, the tyre must be replaced. If you have lost pressure, avoid continuing for long on the flat tyre, because repairable damage can become unrepairable. For a quote you can write to us via WhatsApp.

Question 7

What is puncture sealant liquid and how does it work?

Accepted Answer

It is a sealant that is put into the tyre through the valve, usually with a compressor, to close the hole and reinflate the tyre. It is an emergency solution: for the ContiMobilityKit Continental states tread holes up to 6 mm and to continue at no more than 80 km/h for at most 200 km. Other kits may have different limits, to be read in the instructions. It is not for cuts or sidewall damage; afterwards have the tyre checked by a tyre shop.

Question 8

Does puncture sealant liquid damage the TPMS sensor?

Accepted Answer

It depends on the product. The sensor measures pressure through a small opening and some sealants can dirty or clog it; others are designed to be compatible with TPMS sensors and the residues are removed with water. Before use check whether the kit is declared compatible and follow the instructions of the manufacturer and the car's owner's manual. Always tell the tyre fitter that you used the liquid, so they can clean the tyre and sensor.

Question 9

How far can you drive on a space-saver spare wheel?

Accepted Answer

The space-saver is a temporary solution to reach a tyre shop: the maximum speed and limitations are printed on the space-saver and given in the owner's manual, and must be respected. It has different dimensions and structure from a normal wheel and worsens grip and braking. Check the space-saver's pressure periodically, because it is often forgotten in the boot and deflates.

Question 10

What are run-flat tyres and how do they work?

Accepted Answer

Run-flats have reinforced sidewalls that let you keep driving for a limited distance after a loss of pressure. For its own run-flats Michelin states up to about 80 km at no more than 80 km/h, values that vary with load, temperature and road conditions. They need rims and a car designed for this type of tyre and a tyre pressure monitoring system (TPMS) that signals the drop. After a puncture have the tyre inspected.

Question 11

Can a run-flat tyre be repaired?

Accepted Answer

It depends on the manufacturer, the damage and how the tyre was used after the puncture. Michelin states that its own run-flats can be repaired only once by a professional, with the same procedure as conventional tyres, except those that carry on the sidewall a mark saying they are not repairable. Continental excludes repair in case of structural damage from driving at low pressure. After inspection the tyre fitter decides whether to repair or replace.

Question 12

What should I do if I get a puncture on the motorway?

Accepted Answer

Switch on the hazard lights, move the car to the emergency lane and stop as far to the right as possible. Put on the high-visibility vest before getting out, place the warning triangle (the Polizia Stradale (Highway Police) states at least 100 metres on the motorway) and take passengers to a safe spot, away from traffic. To call for help the Polizia Stradale suggests the SOS emergency phones, which show the exact position; ACI roadside assistance answers on the freephone number 803.116, available 24 hours out of 24.

Question 13

What should I check after hitting a kerb or pothole?

Accepted Answer

Check the tyre and rim straight away: look for bulges or swelling on the sidewall, cuts, deformations and a bent or cracked rim; then see whether vibrations, a crooked steering wheel or the car pulling to one side appear. Internal damage is not always visible from the outside. Michelin states that after an impact to the rim new balancing may be needed and that a change in driving requires an alignment check. If in doubt, have the wheel inspected off the car.

Question 14

What do I do if I lose air from a tyre while driving?

Accepted Answer

Slow down without steering or braking sharply, hold the steering wheel firmly and stop as soon as it is safe. If the tyre is flat, do not continue for a long distance: continuing to drive can extend the damage beyond the repairable area, making the tyre need replacing. Use the space-saver or kit only as an emergency solution and have the tyre checked by a tyre shop.