Most drivers know tyre pressure matters. Far fewer know where to actually find the correct number for their car, and a surprising number are checking against the wrong figure entirely. Here is how to get it right.
The most common mistake: reading the wrong number
The pressure number moulded into the tyre's sidewall is not the recommended pressure for your car. It is the maximum pressure that specific tyre is rated to handle safely. The pressure you should actually run is set by your car's manufacturer, based on the vehicle's weight, suspension, and handling characteristics, and it is usually lower than the tyre's maximum.
You will find the correct figure for your car on a sticker, almost always located on the inside edge of the driver's door frame, inside the fuel filler flap, or occasionally in the glovebox. It is also in the vehicle handbook. Many cars list two figures: one for normal loading and a slightly higher one for when the car is fully loaded with passengers and luggage.
Why getting it wrong actually matters
- Under-inflated tyres increase rolling resistance, which increases fuel consumption, and they wear unevenly along the outer edges of the tread. They also generate more heat at speed, which increases the risk of a blowout on a long, fast journey.
- Over-inflated tyres reduce the contact patch with the road, which can reduce grip and braking performance, and they tend to wear faster down the centre of the tread. They also make the ride noticeably harsher.
- Uneven pressure across the car can affect handling balance, particularly under braking or in wet conditions.
How to check it properly
- Check when the tyres are cold, ideally before the car has been driven that day, or at least after it has been parked for a couple of hours. Driving heats the tyres and temporarily raises the pressure reading, giving a falsely high number.
- Remove the valve cap and press the gauge firmly onto the valve until the hissing stops and you get a steady reading.
- Compare against the figure from the door sticker or handbook, not the tyre sidewall.
- Top up or release air as needed, then refit the valve cap, which helps keep dirt and moisture out of the valve.
- Do not forget the spare, if your car has one. A flat spare is no use in an emergency.
Free places to check pressure. Most petrol stations have a free or coin-operated air pump with a built-in gauge. Many also have digital pumps that let you set the target pressure and stop automatically, which is the easiest way to get it accurate.
How often to check
Once a month is a reasonable habit for most drivers, and always before a long motorway trip or before carrying a heavy load. Tyres lose a small amount of pressure naturally over time, even with no puncture, so a tyre that was fine a few weeks ago is not guaranteed to still be correct now.
What your tyre pressure warning light actually means
Most cars built in the last decade or so have a tyre pressure monitoring system that warns you on the dashboard when a tyre is significantly under-inflated. This is a useful backup, not a replacement for manual checks, since some systems only flag a meaningful drop rather than small day-to-day changes. If the warning light comes on, treat it as a prompt to check all four tyres properly rather than just topping up whichever one seems lowest by eye.
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