If you have a flat tyre, it may be for a number of reasons. Often, inflation pressure loss is a consequence of a tyre puncture, or tyre sidewall damage, but it could also be a leaking valve, valve cap or even the wheel. So what should you do when your tyre goes flat? Let's get to the heart of the matter.
How do I know if my flat tyre is caused by a tyre puncture?
A flat tyre may have suffered a tyre puncture. The puncture may have been caused by a nail, a sharp foreign object that you drove over, an impact to the sidewall or a leaking valve.
Signs that you may have a tyre puncture:
- Sluggish or heavy steering
- Apparent drag in the car when rolling slowly
- A constant pull in one direction
- Increased noise from one tyre whilst cornering
- Warning from tyre pressure monitoring system
- The car not sitting level as you approach it
- A more deformed looking tyre as it sits on the ground
Is driving on a flat tyre safe?
No. Any tyre puncture, no matter the size, must be checked by a qualified professional. It is not safe to reinflate a damaged tyre because you risk rupturing the tyre and an associated rapid deflation whilst you are close to it. Driving on a damaged tyre may put yourself, your passengers and other road users at risk because the car may not handle normally and the tyre may rupture.
Minor tread damage, away from the shoulders and sidewall of the tyre, is often repairable.
But when a puncture or tear occurs anywhere close to or on the sidewall, minor repairs cannot be conducted. In such situations, to ensure that the tyre is serviceable, a repair to the sidewall, referred to as a Major repair, must be used, to ensure that the sidewall is sufficiently reinforced but remains flexible. Often this kind of repair is not economical for a car tyre and not many tyre dealers have the necessary equipment.
Therefore, it might be preferable to replace your tyre with a new one.
Car tyre repairs should only be completed by competent technicians. The repairer may refuse to repair your tyres for a number of reasons such as if they suspect the car has driven on the tyre in an underinflated condition.
There are a number of additional reasons for which a tyre may not be repairable. If you spot any of these your tyre isn’t suitable for repair and needs replacing instead:
- Less than 1.6 mm tread depth in the central ¾ of the tread width
- Bead or structural damage or weakness, including internal corrosion caused by moisture entering via cuts.
- Aged rubber
- Multiple previous punctures
I have a flat tyre that is not punctured nor damaged
In this case, there may be a leaking valve or wheel or it could be that your tyres require more regular maintenance. It is natural for tyres to lose a little inflation pressure over time. As part of regular monitoring, inflation pressure can be topped up periodically, provided the pressure has not fallen enough to cause damage to the tyre.
It is recommended that tyre inflation pressures should be checked at least monthly and before any long journeys. Such monitoring also identifies if there is a change in the rate of inflation pressure loss which might require investigation.
However, if not managed, pressure loss can eventually lead to significant under-inflation, which presents several risks:
- Under-inflation shortens the life of the tread by increasing the wear rate in general but in particular on the outer edges (or shoulders) of the tyre.
- Under-inflation can also cause over flexing and overheating, which increases rubber wear rates but also weakens the tyre structure.
- Under-inflation can affect handling and performance, for example under heavy braking, especially in wet weather.
- Under-inflation increases fuel consumption by increasing tyre rolling resistance, which means more frequent stops at service stations and higher fuel costs.
To avoid these problems, it is important to check the pressure of your tyres regularly, regardless of the type of vehicle you drive.
What tyres can prevent puncture?
MICHELIN tyres with Selfseal® Technology avoid pressure loss from punctures in the tread and immediately seal tread penetrations less than 6mm diameter. This protects the tyre for a limited period until the puncture can be repaired.
MICHELIN ZP tyres are identified by the ZP logo on the sidewall. They have a reinforced sidewall to support load for a limited period in event of a loss of inflation pressure.
With a MICHELIN ZP tyre you can continue driving, but at a maximum speed of 50mph for a maximum distance of 50 miles, to allow you to find a dealer to repair or replace the tyre. If more than one tyre is punctured, you should not continue driving.
Know more about runflat tyres.