Why tyres lose pressure and how to fix it

The right tyre pressure is more important than you might think – it affects your fuel economy, comfort, and most importantly, your safety on the road.

Underinflated tyres can lead to blowouts and accidents, so it’s vital you keep an eye on your pressure and top up when needed. Low pressure can also cost you money; you’ll use more fuel per mile, and the increased friction with the road surface wears your tread out faster.

At Halfords we know our tyres. So, here's our at-a-glance guide to low tyre pressure problems and how to tackle them.

If you're wondering why your tyres lose pressure when you’re not driving, there's a simple answer. Tyre pressure loss can be a natural process which can be made worse by other factors. The first step towards keeping your tyres safe is to understand the causes of pressure loss.

• Osmosis. As soon as you've inflated a tyre, it starts to lose pressure because tiny amounts of gas will pass through anything solid, including those stout reinforced rubber walls. The fall in pressure from permeation alone can be up to three pounds per square inch (PSI) per month. It happens so gradually that you may not notice the decline in driving performance until something bad happens.
• A small, slow puncture. Even a microscopic tear in the tyre is an additional escape route for the air within.
• Changes in temperature. As a rule of thumb, when the temperature falls by 10°C, tyre pressure drops between 1 to 2 PSI.
• Damage to the wheel rim. If the wheel is distorted even slightly, the tyre will also lose shape, causing it to leak more air than normal.
• Faulty, damaged or defective valves. When a tyre valve works properly, no air can escape through it. Defects can result from general wear and tear and any damage will make the valve less airtight.
• Damaged or compromised tyre bead. The bead is the part of the tyre that forms a seal with the wheel. If even a tiny object lodges between bead and wheel, or if the bead gets damaged, there's a breach through which air can escape.

At Halfords, we recommend a monthly tyre pressure check, even if you're doing little or no driving. To stay safe and save money, it's also wise to check your tyres more frequently when doing a lot of driving. As well as using a tyre pressure gauge and reinflating as required, inspect the tyres for damage. That will help to pre-empt problems before they become serious, or even dangerous.

Read our simple guide to checking and inflating tyres.

Or, if you’d rather let us do the hard work for you, book a FREE Tyre Check at your local Halfords garage. We’ll check your pressure, tread depth, and the general condition of your tyres to spot any signs of damage. If there are any, we’ll advise you on what to do next.

If it’s time for new tyres, we can help with that too – there’s plenty of brands to choose from, to suit any budget. And best of all, we have a variety of fitting options, from right on your driveway with our mobile tyre fitting by Halfords Mobile Expert to same day tyre fitting at one of our garages.

With most modern vehicles, the manufacturers incorporate a tyre pressure monitoring system (TPMS) with sensors on each wheel. There are two different types of TPMS, direct and indirect, but the principle is the same: if the sensors detect a drop in pressure, this will activate a warning light on the dashboard. However, it’s still important to monitor tyre pressure regularly as this can sometimes decline gradually and may not be picked up by your TPMS.

In a similar vein, there is also the chance of receiving a false alert. A little knowledge can prevent a lot of hassle, so it's worth knowing how your TPMS works—and what to do if it triggers needlessly. Take a look at our guide to TPMS, which includes advice on booking a TPMS health check if you suspect it might be faulty.