One critical, often overlooked, part of your car that requires regular attention is tyre pressure. With the right tyre pressure, you can ensure a safe and smooth ride, better fuel efficiency, and an extended lifespan for your tyres.

In this blog, we'll delve into the vital aspects of tyre pressure and what the signs of low tyre pressure are, how to check whether your tyre pressure is low and what you should do if the tyre pressure warning light in your car turns on.

What is tyre pressure?

Tyre pressure refers to the amount of air in your car's tyres, typically measured in pounds per square inch (PSI) or BAR.

Having the correct tyre pressure is critical for vehicle safety, performance, and fuel efficiency. The optimal pressure for your tyres depends on several factors, including vehicle type, tyre size, load weight, and driving conditions.

Different car manufacturers recommend different tyre pressures for their models. For instance:

• Fiat 500 tyre pressure is between 29 to 32 PSI
• Ford Fiesta tyre pressure is between 32 to 35 PSI

Therefore, it's essential to refer to your vehicle's owner manual to know the recommended pressure.

What are the signs of low tyre pressure?

Identifying low tyre pressure is crucial to maintaining your car's performance and safety. Some tell-tale signs of low tyre pressure include:

• Uneven tyre wear: this can signify that part of the tyre is over-inflated while another part is under-inflated
• Vehicle pulls to one side: if your car consistently leans to one side while driving, it might indicate a tyre pressure issue
• Vibration or thumping when driving: this is often a sign of low tyre pressure or a damaged tyre
• Reduced fuel efficiency: since under-inflated tyres increase rolling resistance, your car needs to work harder, which consumes more fuel
• Tyre pressure warning light turns on: the tyre pressure warning light is a dashboard indicator that one or more of your tyres are significantly under-inflated

However, the most reliable method of detecting low tyre pressure is through a tyre pressure check using a proper tyre pressure gauge.

How to check tyre pressure

Checking your tyre pressure is a relatively simply process and can be done using a tyre pressure gauge. You will need to purchase one if you don’t have one, and then follow these steps:

1. Ensure your tyres are cold – driving warms up the tyres and increases pressure causing an inaccurate reading
2. Remove the valve cap from one of your tyres
3. Press the tyre pressure gauge onto the valve stem and hold it down firmly. If you’re hearing a hissing sound, it means you’re letting air escape so press down firmly
4. Read the pressure indicated on the gauge and compare the reading to what’s in your owner’s manual
5. Repeat the above steps for each tyre

If your tyre pressure is not within the recommended range specified in your vehicle's owner's manual, it's important to adjust it accordingly. Here's what you can do:

If your tyre pressure is too low:

1. Locate an air pump: you can usually find air pumps at most petrol stations
2. Double check your current tyre pressure: most air pump machines have built-in tyre pressure gauges. Remove the valve cap from your tyre, connect the air pump and check the reading
3. Inflate your tyre: if the reading is lower than what's recommended in your owner's manual, add air to your tyres. Make sure to check the pressure intermittently to avoid overinflation
4. Replace the valve cap: once you've inflated your tyres to the recommended pressure, disconnect the air pump and replace the valve cap

If your tyre pressure is too high:

1. Let out some air: press the pin on the tyre pressure gauge in the centre of the tyre valve, releasing some air
2. Check the pressure: after letting some air out, use your tyre pressure gauge to check the pressure again
3. Repeat as necessary: continue releasing air and checking the pressure until your tyres are at the recommended pressure

Sometimes, even after adjusting the tyre pressures, the warning light might stay on. In this case, there could be an issue with the TPMS or another related system, and you should get it checked out by a mechanic

When is it time to see a professional mechanic

Although low tyre pressure is usually an easy thing to fix yourself, there are some instances where you should consult a mechanic. These are:

1. If the tyre pressure warning light is flashing: this could indicate a problem with the monitoring system itself, and it might need a check-up or repair
2. If your tyres frequently lose pressure: if you find yourself frequently needing to top up your tyres with air, you could have a slow leak. It's best to get this checked out, as driving on under-inflated tyres can cause additional wear and damage
3. If there's noticeable damage to a tyre: if you can see visible damage, like cuts or punctures, it's best to get it checked out by a professional. They can determine whether the tyre can be repaired or if it needs to be replaced

If you need to get your tyre pressure checked, you can book with vetted mechanics near you in Caura

Will low tyre pressure result in MOT failure?

Low tyre pressure itself is not a direct reason for failing an MOT test. However, if low tyre pressure leads to other observable problems, such as significantly worn or damaged tyres, it will result in a failure.

Here are 3 tyre-related issues that can cause an MOT failure:

1. Tread depth: the legal minimum tread depth in the UK is 1.6mm. If any of your tyres are below this, your vehicle will fail the MOT
2. Condition of the tyres: if the MOT inspector finds any cuts or other damages on your tyres that could jeopardise safety, you will fail the MOT
3. Badly fitted tyres: while the condition of the spare tyre isn't part of the MOT test, a badly fitted tyre that's in use can cause a failure

Read more about what can cause an MOT failure here.

Remember to check your tyre pressure regularly (at least once a month) and before any long trips. It's also important to remember that properly inflated tyres can help you achieve better mileage and ensure your vehicle's handling is as effective and safe as possible.

Ready to book your MOT? Book now via trusted garages near you in Caura!

*Image credit Flickr user Brent Payne