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Telltale signs you have a slow puncture

Not sure if you have a slow puncture in one of your tyres? We discuss the signs to look for, and what you should do next

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A straightforward tyre puncture is easy to detect, but a slow puncture – not so much. Usually caused by small nails or other sharp debris piercing a small hole in the tyre tread, slow punctures are pretty common, and you could be driving around for days or even weeks without knowing you have one.

Luckily, there are a few telltale signs to look out for and, if you do have one, a slow puncture does not always mean that the tyre needs to be replaced.

What is a slow puncture exactly, and why do I need to repair it right away?

A slow puncture is essentially a tiny hole that slowly deflates the tyre over time. They are usually caused by driving over small sharp objects that have ended up on the road, driveway or country path. You can also get a slow puncture by not slowing down for a particularly rough or deep pothole, or from a damaged or rusted wheel rim, but those are less common.

Because a car tyre is very strong in its construction and is filled with air under much higher pressure than the air outside the tyre, a very small hole in the tyre wall may initially remain closed much of the time. But as the load on the tyre temporarily shifts (maybe under braking, acceleration or steering), it opens up to allow a small amount of air out. Each time this happens, more and more air gradually escapes.

Ignoring a slow puncture can lead to a larger tear or even a sudden tyre blowout. Slow punctures reduce the air pressure of your tyre over time, and under-inflated tyres make your car more prone to breakdowns and road accidents. In addition, a low pressure tyre with a slow puncture also increases your braking distance, and can affect your car’s steering too.

What signs should I look out for?

One of your tyres always needs more air than the others

This is the most obvious way to spot a slow puncture. If you regularly inspect your tyres at the petrol station or at home, you may find that one of your car’s tyres has a lower pressure gauge reading than the others. If this happens, it is worth checking the tyre for any small stowaways embedded in the tread.

Your car is pulling or drifting to one side

While driving at a safe speed on a straight flat road, briefly relax your grip on the steering wheel and see if your car pulls slightly to the left or right with no prompt. If it does, this suggests that there is a problem with your tyres. This could be a slow puncture, though it could be a hint that your wheels aren’t aligned properly too.

Your steering wheel is vibrating

A low-pressure tyre with a slow puncture is rather unstable and prone to overheating under stress. You might be able to feel this instability through the steering wheel when driving at high speeds on the motorway.

Your car is not as responsive as it was

If your car’s steering feels more sluggish than usual, or the suspension is noticeably more rigid, it is wise to check your tyre pressures to see if they are all equal.

When should I check my tyres?

You may be surprised to read that tyre manufacturers recommend checking your tyres on a monthly basis anyway, even if you don’t necessarily harbour a suspicion that anything is wrong.

Even without a puncture, your tyres will gradually lose air over time, so it is a good idea to check your tyre pressure every once in a while – preferably when your tyres are cold so that you don’t get any false pressure readings.

If you do spot any of the telltale signs above, then you really should inspect your tyres before you set off again. Start with a visual inspection, looking for any embedded objects and comparing the tyre to the other three to see if it looks more deflated than usual. Then check your tyre pressure with your own pressure gauge, or you can drive to the nearest petrol station and use the air pump machine.

I have a slow puncture. What now?

Now, we need to find an experienced technician. Visiting your nearest garage or repair centre will put you on the right track.

If the puncture was caused by a small nail or screw, you often won’t need to replace the tyre. Instead, a technician can repair the hole left by the debris by fitting a rubber plug in its place – job done.

However, if the slow puncture has been neglected and damage has spread to the tyre’s sidewall, or if the puncture was caused by a damaged wheel rim, you are likely to need a replacement tyre, and additional new parts if more than the tyre is damaged.

Also, a slow puncture repair is not as straightforward on a high performance tyre. These tyres are designed to withstand higher levels of stress and strain than an ordinary tyre, or the standard rubber plug fix usually won’t be up to the job.

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Sean Rees
Sean Rees
Sean is a content editor at The Car Expert. A enthusiastic fan of motorsport and all things automotive, he is accredited by the Professional Publishers Association, and is now focused on helping those in car-buying need with independent and impartial advice.
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