Check monthly and before long journeys. Under-inflated tyres can overheat and fail at motorway speeds. Over-inflated tyres reduce grip and braking ability. Both affect fuel economy.

Finding the Correct Tyre Pressure

The correct pressure for your car is specified in PSI (pounds per square inch) or bar. Find it in one of these places:

Driver's door jamb sticker, on the edge of the door, visible when the door is open (most reliable)
Inside the fuel cap
Owner's handbook

Most cars specify different pressures for front and rear tyres, and a higher pressure for when carrying a full load of passengers and luggage.

Typical Pressures (as a guide)

Small cars (Fiesta, Polo, Corsa): 30–32 PSI front / 28–30 PSI rear
Family cars (Focus, Golf, Astra): 32–35 PSI front / 30–33 PSI rear
SUVs & crossovers: 33–36 PSI front / 32–35 PSI rear

Always check your door sticker, these are typical values only and your car may differ.

Step-by-Step: How to Check Tyre Pressure

Check tyres when cold, wait at least 2 hours after driving, or check before you've driven for the day. Driving heats the air inside the tyre and raises the pressure reading.
Remove the valve cap from the tyre valve stem (the small rubber or metal stem on the inner edge of the wheel). Keep the cap safe.
Press a tyre pressure gauge firmly onto the valve. You can buy a small digital gauge for under £10, or use the gauge at a petrol station forecourt (most are free or cost 20–50p).
Read the pressure. Compare it to the recommended value for that tyre (front or rear).
Inflate if needed. At a petrol station, use the airline. Set the target pressure on the machine and press the head onto the valve until it beeps or stops. Alternatively, use a portable compressor at home.
Release air if over-inflated by pressing the small pin inside the valve stem with the back of the pressure gauge or a small tool.
Replace the valve cap.
Repeat for all four tyres (and your spare if you have one).

Checking Tread Depth

While you're there, check the tread depth. The legal minimum in the UK is 1.6mm, but 3mm is recommended for safety in wet conditions. The easy test: take a 20p coin and insert it into the main tread groove. If you can see the outer band of the coin, the tread is below 3mm. If you can see the inner lettering, it may be at or below the legal minimum, replace immediately.

Also check for any cuts, bulges, or embedded objects (nails, screws). A bulge in the sidewall means the tyre structure is damaged and the tyre must be replaced urgently.