Flat Tyre: How to Check for a Slow Tyre Puncture

By David Sholicar

Most drivers never give their tyres a second thought, apart from the occasional check to see whether the pressure is correct; however, the safety of you and your passengers depends heavily on your tyres being fit for purpose.

Slow Tyre Puncture

Most drivers never give their tyres a second thought, apart from the occasional check to see whether the pressure is correct; however, the safety of you and your passengers depends heavily on your tyres being fit for purpose. Garages will notify you if any of your tyres need replacing after MOT tests or regular service checks of your vehicle, but ideally you should be checking your own tyres every week to make sure that they are roadworthy.

Tyres that are correctly inflated and have the appropriate amount of tread are less likely to suffer from damage than tyres that are worn or underinflated. Legally a tyre must have a tread of at least 1.6mm across three-quarters of the tyre's width; however, most manufacturers recommend replacing a tyre if the tread wears down to less than 3mm. Below this level of tread, your car's road holding and braking performance could be compromised.

Try to establish a routine of checking the tread across all your tyres once a week, preferably while checking the air pressures. Do not forget the spare tyre, if you have one, as there is nothing quite so frustrating as going to replace a punctured tyre only to discover that your spare tyre has insufficient air to support your vehicle.
Check your car's handbook for your model's correct tyre pressures. Do not rely on a visual inspection when it comes to air pressure, as appearances can be deceptive. Bear in mind that tyres can lose as much as two pounds of pressure over a four-week period and that air temperature can affect tyre pressure; therefore, you may see seasonal variations in the amount that needs topping up.

If you notice that a tyre is losing more than two pounds of pressure in a month, you may have a slow puncture. Most people will experience at least one of these during their driving career and knowing what to do can help you to avoid unnecessary expense later.

Many people are tempted to carry on as normal when they have a slow puncture, topping it up now and again when it looks a little flat, but doing this is compromising your safety. A partially deflated tyre is unstable, offering less grip and potentially making your steering unsafe. If the slow puncture leads to a blowout, you could face serious injury or even a fatality if it occurs at speed.

Many slow punctures are due to a leaking valve and you can easily check whether this is the case. Simply rub some soapy water around the valve after inflating the tyre and watch to see whether any bubbles form as air escapes. If this is the case, you simply need to arrange for a replacement valve to be fitted.

If the valve is not the issue, you need to find the puncture spot. You could do this yourself by removing the tyre and placing it in water to track where bubbles indicate air escaping; however, it is far easier to visit us at Protyre. We will conduct tests and let you know whether the tyre can be repaired or needs replacing.

Cause of punctures

In our experience, most tyre punctures occur when cars drive over sharp objects at high speed, resulting in the object puncturing the tyre. This then leads to either a slow or quick tyre deflation, which if it occurs at high speeds, can be extremely dangerous. Other heavy impacts such as driving into a kerb at high speed or driving over a pothole can also result in deflation. However, years of experience also tell us that there are other factors that can lead to a tyre puncture. These include:

  • A tread that has been worn down to an excessive degree which then results in normal road debris ripping through the tyre. Worn out treads can also lead to the tyre exploding.

  • A leaking valve stern.

  • A collision resulting in damage to the connection between the rim and the tyre.

Can you repair the tyre?

This depends on a number of factors, but it’s good practice to inspect the tyre thoroughly before you decide to do so. British standard BSAUI59 outlines the repair materials that can be used and the number of repairs that can be made based upon the location of the puncture and the size of the tyre.
If the tyre has any of the following a repair should never be attempted:

  • Previous repairs that appear faulty.

  • A tread that has been worn down to 1.6mm or below.

  • Cords that are exposed.

  • Rubber that is aged, worn and deteriorated.

  • Damage to the structure of the tyre.

If you’re looking for a range of the best tyres from leading manufacturers such as Pirelli, Falken, Sumitomo or Bridgestone, Protyre can help. Just use our simple search function to locate the best tyre for your vehicle. Alternatively, you could head down to one of our many garages where our tyre professionals and qualified fitters will give you their expert opinion and agree the best option with you.

How to fix a punctured tyre

Before attempting to fix a punctured tyre, you need to ensure the environment is safe to do so. Under no circumstances should you attempt to change a tyre on the hard shoulder of a motorway, it is far too dangerous. Remove all passengers from the vehicle and apply the handbrake.

Locating the puncture

The location of a puncture is extremely important to determine whether it is safe to repair it, or whether a replacement tyre is required. If the puncture is within the Minor Repair Area (central ¾ of the tyre) then a repair can be carried out but if it is too close to the sidewall, then it is classed within the Major Repair Area and the tyre will require replacing. This is because the sidewall of a tyre withstands the greatest load and therefore a minor repair may not be suitably safe.

tyre puncture

The blue section on this image indicates the Minor Repair Area where a puncture can be safely repaired. The red sections displays the Major Repair Area where a puncture will result in the tyre needing to be replaced.

Using your tyre repair kit

  • Always refer to the instructions in your repair kit or your vehicle handbook before attempting to fix a puncture.

  • Squeeze all of the sealant into the tyre using the repair kit adapter

  • Attach the compressor valve

  • Using either your vehicle’s cigarette lighter or 12v socket, plug in the compressor

  • You may be required to roll your vehicle forward to make sure the sealant spreads throughout the tyre

  • However, some repair kits supply an additional adapter which will allow you fit the sealant bottle into the compressor – this will enable you to pump the sealant into the tyre via the compressor

Once you have followed these steps, pump up the tyre. Put your vehicle in neutral, start the engine and turn on the compressor. Ensure you inflate the tyre to the correct Bar/PSI – check your vehicle handbook.

Replacing the damaged tyre

When your tyre is sufficiently inflated, drive to the nearest Protyre garage to get the tyre inspected by our experienced and trustworthy technicians. Do not exceed the recommended speed found in your vehicle handbook. If your tyre needs replacing, our technicians will be able to offer you free, impartial advice on the best replacement tyre for your vehicle.
With a large and rapidly-growing UK garage network, finding a Protyre garage near you is simple…just use our garage locator by clicking the button below and entering your postcode.

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Assessing the condition of a punctured tyre

Protyre will check the tyre thoroughly to locate the puncture. If the wheel is damaged, there is a hole greater than 4mm in the tread, or the tyre’s sidewall is ripped then the tyre will need replacing.

Can a Run Flat tyre be repaired?

When a run flat tyre gets punctured it can be difficult to determine whether the structure of the tyre wall has been compromised. The additional strength of a run flat tyre can make it problematic to identify the extent of the damage, especially as it could have been driven on for too long, or over the recommended speed of 30mph. Therefore, although Protyre can carry repairs to run flat tyres, it is circumstantial and recommended that a replacement tyre is purchased.

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About the author

Article Author Photo
By David Sholicar
David is the National Retail Operations Manager for Protyre. One of David’s areas of responsibility and expertise is dealing with the DVSA and MOT’s for Protyre. As the Authorised Examiner Designate Manager ( AEDM ) David deals with applications for changes to the many Vehicle Testing Stations ( VTS’s) including managing the growth of the Number of MOT testing stations that Protyre operate, allocating MOT tester roles, and monitoring the MOT Test logs to ensure that Protyre MOT standards are maintained as the best in the industry.
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