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How to check tyre pressure

WHAT IS THE RECOMMENDED TYRE PRESSURE?

WHAT IS THE TPMS?

FAQs

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Tyre pressure is the amount of air in your tyre usually measured in pounds per square inch (PSI) however also can be stated in BAR or kPa (Kilopascal). The air inside your tyres carry the total load of your vehicle, so getting this aspect of maintaining your car right is key. If your tyres are under-inflated, your vehicles handling and braking could be thrown off and also the sidewalls could break down, leading to a blowout. Over-inflated tyres are also at greater risk of blowouts and they can cause your vehicle to lose traction. In addition to the safety concerns, tyres with the wrong amount of air in them are likely to wear out much faster than those with the correct pressure, so you’ll have to shell out money for new ones much sooner. Under-inflated tyres also reduce the fuel mileage of a car or truck. It’s safe to say that incorrect tyre pressure is not going to do wonders for your bank account. As you can see, there are plenty of reasons for maintaining the right tyre pressure, so let’s take a look at how to check your tyre pressure in 7 steps.

1. Get an air pressure gauge

First, you need the right equipment: a pressure gauge and an air compressor. There different types of tyre gauges including digital, dial or “stick” type gauges. After reading the pressure displayed on the gauge, you will also need a compressor to fill any low tyres, although in a pinch you could use a manual pump (be ready to break a sweat). Both of these pieces of equipment are usually available for purchase at Autocentres or petrol stations.

2. Find the correct pressure

Many drivers make the mistake of looking on the tyre’s sidewall to find the right pressure. The pressure stated on the tyre itself is the maximum pressure, which is not the optimal pressure for your vehicle. The correct tyre pressure setting for your vehicle are provided by the vehicle manufacturer, these pressure settings has been tested and developed to both sufficiently carry the required load and match specific characteristics of your vehicle. You can find this specification (usually given in PSI) on a plate inside the driver’s side door jamb, inside the fuel filler flap or in your owner’s manual. Note that this value will be the cold pressure, which can be measured before driving on your tyres or exposing them to the heat of the sun. Hot air expands, so hot tyres will show a higher pressure reading than cold ones.

3. FIND VALVE AND REMOVE CAP

Now that you have your tools and you know the right pressure, find the valve, which is a little tube poking through the wheel that the tyre is mounted on. It will usually have a small cap on it. Unscrew the cap and save it in a safe place so you can screw it back on later.

4. PUSH THE GAUGE ONTO THE VALVE STEM

The tip of your gauge has a round, flat face on one side with a smaller round protrusion inside it. You need to fit this face firmly over the top of the stem and push down. If air is hissing out around the edges, adjust the gauge until it forms a seal around the valve stem. Air from inside the tyre will rush into the gauge and indicate the tyre’s current pressure.

5. ADD AIR IF NEEDED

If your tyre is low, you’ll need add more air with an air compressor. Usually your local tyre dealer will check and inflate your tyre pressures at no cost. However if you cannot get to a tyre dealer or you do not own a compressor your local petrol station should also have a compressor. Compressors are often fitted with a tip that looks somewhat like a pistol, with a “trigger”—a lever similar to the ones that fire extinguishers are equipped with. Fit the tip of the “pistol” over the valve and pull down the lever to start the flow of air into the tyre. You should hear the muffled sound of air entering, like the noise of a balloon when you are blowing it up. If you hear sharp hissing sounds, this means that the compressor tip isn’t seated right on the valve and air is escaping out of the sides instead of going into the tyre.

6. CHECK OFTEN

As you are inflating the tyre with air, frequently re-check the pressure using the gauge as described in step four so you don’t overfill your tyre. Once you reach the recommended amount, you can screw the valve cap back on and move on to the next tyre.

7. IF YOUR TYRE HAS TOO MUCH AIR

If you put too much air into your tyre with the compressor or you have found that your tyre was well above the recommended pressure when you originally checked it with the gauge, you will need to remove air. You can use the tyre gauge to do this. The tip of the gauge has a small protrusion opposite the flat face used to check pressure. Use this protrusion to depress the small pin with a round head that is inside the valve stem on the wheel. This releases air from the tyre. If you are successful, you will hear air rushing out of the tyre. Continue releasing air and checking the pressure until you have reached the recommended PSI reading. Remember, recommended PSI values are for when the tyres are cold, so if the tyres are hot and a few PSI over the recommendation, you don’t need to release air.

WHAT IS THE RECOMMENDED TYRE PRESSURE?

The recommended tyre pressure is a specification given by the manufacturer based on how much the vehicle weighs, how much weight it is designed to carry, and other factors like suspension, performance, and handling. You can find this value on a plate inside the post of the door on the driver’s side, inside the fuel filler flap or in your owner’s manual. This specification is not to be confused with the tyre’s maximum pressure rating, which is moulded onto the tyre itself. This maximum rating is provided by the tyre manufacturer and usually exceeds the recommended pressure.

WHAT IS THE TPMS?

Starting in 2014, all new cars in the UK are required by law to be equipped with a tyre pressure monitoring system (TPMS) as a safety feature. These systems use a piece of hardware attached to the back of the valve stem or a combination of sensors in other systems to alert you when your tyre pressure is severely low. When this happens, you will get a TPMS warning indication, this looks like a light shaped like a letter “U” with an exclamation mark in it lights up on your dashboard so you know that you need to check and fill your tyres.

FAQs

What does it mean when your car shows "check tyre pressure"?

When your vehicle tells you to check your tyre pressure or when the TPMS light is on (a U-shaped symbol with an exclamation mark in it that lights up on your dashboard), this means that one of your tyres is significantly below the recommended pressure and needs to be inflated.

Can you drive with low tyre pressure?

Driving with low tyre pressure is dangerous and can also damage the tyre, meaning you’ll have to buy a replacement. If your tyre pressure is low, you should follow the steps laid out in this article to fill it back up to the recommended pressure as soon as possible.

What happens if you don't check the tyre pressure?

If you don’t check your tyre pressure regularly or when refilling a tyre, your tyre may have too much or too little air in it. Over time, this wears out the tread, which makes the tyre perform poorly and means that you’ll have to replace it sooner. In severe cases, a tyre with the wrong pressure could blow out and cause an accident.

What's the lowest tyre pressure I can drive on?

It isn’t advisable to drive on a tyre that’s lower than the recommended value. A pressure that is 25% below the recommended one is considered severely low. If it is absolutely necessary to drive on a low tyre, go slowly and use extreme caution.

Where can I check my tyre pressure?

Many petrol stations have a tyre pressure gauge on the forecourt so you can check and fill your tyres for around 10-50 pence. However, these gauges can be inaccurate, so it is beneficial to have your own.

Nearest dealer

If you still have questions about your tyres’ pressure or any other aspect of this crucial part of your car, or you are struggling to check and fill your tyres, find your nearest tyre dealer and they can help you get up and running safely.

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