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How to check tyre pressure

28th September 2021

How to check tyre pressure

Struggling to remember the last time you checked your tyres were correctly inflated? Or perhaps you’re unsure how to measure your tyre pressure in the first place? You’re not alone. A survey from Highways England found that nearly a third (32%) of road users carry out basic vehicle maintenance, like checking their tyre pressure, at best every few months – or not at all. 
As a general rule, you should check your tyre pressure every 30 days, every 10-degree change in temperature, and/or before long journeys. Keep reading our guide to discover how to find your recommended PSI, check your tyre pressure and fill your tyres with air. 

Why do I need to check my tyre pressure?

As the only point of contact between your car and the road, your tyres play a key role in keeping you and your passengers safe. Both overinflated and underinflated tyres can lead to a breakdown or accident on the road, such as a slow puncture or burst tyre when driving at a high speed.  
Poorly maintained tyres can end up being more expensive in the long run, too. Not only can you incur avoidable garage costs having to repair or replace your tyres early, but you can also spend more on your fuel. Tyres with insufficient pressure increase your car’s resistance with the road, so your engine will be working harder and costing you more. Experts have predicted that correctly inflated tyres can improve your mileage per tank by up to 3%. 

How to monitor your car’s tyre pressure

Start off by finding out your recommended PSI

In most modern vehicles, your tyre pressure recommendations can be found on the inside of the driver’s door, but the easiest thing is to look in your manufacturer’s handbook. All tyres have a recommended PSI number which stands for pounds per square inch. This number is a calculation of the amount of pressure that has been pumped into the inner lining of your tyre. With the PSI number, you can find out if your tyres are over or under inflated. 
While most tyres have a PSI of around 30-35, it’s important to remember that the PSI value can differ between each tyre. For example, your two front tyres could have a PSI of 35, whereas your back two tyres could have a PSI of 30

Then you’re ready to check your tyre pressure

You can perform tyre pressure checks electronically and manually: 

Electronically – using your car’s tyre pressure sensors

Most modern vehicles are now fitted with a tyre pressure monitoring system (TPMS), which takes an electronic reading of each tyre’s air pressure. If your TPMS alerts you to a problem with your tyres, a warning light will appear - and you will be required to manually check your tyre pressure. Once the issue has been fixed, the warning light should disappear.

Manually – using a tyre pressure gauge

Alternatively, you can check your tyre pressure manually with your own tyre pressure gauge or, for a small fee, using one at a petrol station or service station. Before you start, make sure you’re using a tyre pressure gauge that uses the same unit of measurement as the pressure guidelines given for your car. Then follow these easy steps: 

  • Remove the valve cap from your tyre 
  • Press the pressure gauge onto the valve stem 
  • Wait for the hissing sound to stop and the gauge will give you a PSI reading 
  • Write down the readings for each tyre 

Now it’s time to adjust your tyre pressure

Filling your tyres with air

Underinflated tyres can lead to premature wear from increased friction. They will increase stopping distances and effect your vehicle’s handling. In just a few steps, you can inflate your tyres to the correct levels: 

  •  If you’re inflating your tyres at a service station or petrol station, you’ll need to put money in the machine 
  • Set your recommended pressure on the machine screen 
  • Put the air compressor hose onto the valve stem and fill until your tyres reach the correct PSI levels 
  • At this point, the hose will hiss - and the machine will make a beeping sound
  • You can then remove the hose and replace the valve stem cap 

 Let air out if necessary

Your tyres become overinflated if they are filled up with too much air, which can lead to a bouncy ride and an ill-handling car. Overinflated tyres can’t absorb shocks as well as correctly inflated tyres, which makes them prone to tyre damage.  

  • If your tyres are overinflated, you can let air out by simply pressing the metal pin inside the valve stem with a screwdriver 
  • You should do this in bursts and check the remaining pressure regularly. 
  • Once your tyres have reached the correct pressure, remember to screw the cap back on the valve stem 

Don’t forget the spare tyre

Don’t forget to check the spare tyre as well. This is often overlooked, and you never know when you might need to use it.  

However, if you’re still unsure about how to check your tyre pressure, or put air in your tyres, book in for your free tyre pressure check with Merityre Specialists. Simply locate your nearest Merityre branch, or get in touch with a member of our friendly team to find out more about your tyre pressures.