What should your tyre pressure be?

Tyre pressure determines how the tyre sits on the road. Low pressure increases fuel consumption and heats up and wears the tyre at the sidewalls. High pressure reduces grip and wears the centre of the tread. The good news is that finding the correct value is very easy.

Where is the correct pressure shown?

You look for the correct pressure for your car not on the tyre, but on the car itself:

• Label on the edge of the driver's door: The most common place. You'll see it on the door pillar or the edge of the door when you open it.
• Inside the fuel filler flap: Some makes put the label here.
• Owner's manual: Shown as a table in the tyres and wheels section.

The "Max. Pressure" value on the tyre sidewall is the highest pressure the tyre can withstand. It is not the driving pressure; don't inflate the tyre to that value.

How to read the label

The label usually has several lines:

• Tyre size: The car's factory sizes. If there is more than one wheel option, each is on a separate line.
• Front and rear pressure: The values for the front and rear tyres may differ.
• Normal load and full load: A higher pressure is recommended when the car is fully occupied, the boot is loaded or you are towing a trailer.
• Eco value: Some cars show a slightly higher "eco" pressure for fuel saving. Comfort is slightly reduced at this value.

Units: bar, kPa and psi

Most air pumps at petrol stations in Turkey show bar or psi. If you get confused: 1 bar is about 14.5 psi.

When should pressure be measured?

Pressure should be measured when the tyres are cold. After the car has travelled a few kilometres, the tyre warms up and the pressure rises by 0.2–0.3 bar. If you measure a warm tyre and let air out, the pressure will be too low once the tyre cools.

It's best to measure after the car has stood for at least two or three hours, or after driving no more than a few kilometres. If you've arrived at the petrol station after a long drive, treat 0.2–0.3 bar above the label value as normal.

How often should it be checked?

• Once a month and before every long journey
• When the seasons change (when the air gets 10 °C colder, pressure drops by about 0.1 bar)
• Don't forget the spare tyre

Tyre pressure monitoring system (TPMS)

From 2014, a tyre pressure monitoring system became mandatory on new passenger cars sold in Europe. There are two types of system:

• Direct (sensor-based): A sensor inside each wheel measures the pressure. You can see the pressure of each tyre individually on the display.
• Indirect (ABS-based): Estimates a pressure drop by comparing the rotational speeds of the wheels. The system must be reset (calibrated) after adjusting the pressure.

A TPMS warning is a reminder; it doesn't replace regular checks. Many systems don't warn you until the pressure has dropped significantly.

Is nitrogen filling necessary?

Filling tyres with nitrogen instead of air can make the pressure drop slightly more slowly. However, air is already about 78% nitrogen. In normal use, regular pressure checks make a much bigger difference than nitrogen. It is also safe to top up a nitrogen-filled tyre with normal air when needed.

Signs of incorrect pressure