Properly inflated tyres will last longer, increase your car's fuel efficiency and give you more control while driving. Under-inflated tyres are more likely to suffer a blowout, which could be very dangerous if it occurs when you are travelling at high speed. It is important that you know how to check your tyre pressure so that you can keep them inflated to the right level.
TyreSafe.org recommends checking the overall condition; tread depth and pressure of your tyres, as well as looking for any bulges or signs of irregular wear, every couple of weeks. However, looking for obvious signs of deflation when you are walking to your car is a good habit to get into.
Checking by eye is not a reliable way to gauge the pressure of your tyres, so use a pump that can test and inflate your tyres at home or visit a petrol station to get an accurate reading. Make sure you perform the test when the tyres are cold, as the heat of friction after a journey of more than a couple of miles will give an inaccurately high pressure reading.
The pressures should be checked against the vehicle manufacturer's recommended levels, which can be found in the handbook. The information may also be on the inside of the fuel filler flap or driver or passenger door. Cars carrying luggage or passengers have different recommended pressure levels, so be sure to choose the correct one. Check the spare tyre at the same time you are doing the others.
In a petrol station, set the digital display to the correct pressure. You will not need to be able to see the screen as a beep will sound when the correct pressure is reached, whether that involves deflating or pumping the tyre. To attach the pump, find the valve and remove the dust cap by twisting anti-clockwise. Pushing the pump onto the valve will start the testing and airflow automatically. Remove the pump when the beep sounds, remembering to replace the dust cap.
For a foot pump the steps are the same, but you must put the lever in the 'lock' position once the pump is attached to the valve. Then check the pressure gauge yourself and add air as necessary.