How Temperature Affects Tyre Pressure

The air pressure inside your tyres is affected by the ambient conditions outside. Warm ambient temperatures cause high tyre pressures, while colder ambient temperatures result in lower tyre pressures. In science talk, the heat excites the air particles inside your tyre, making them expand and take up more space, consequently increasing the air pressure inside.

Which factors affect tyre pressure?

Because of this fluctuation, it’s important to consider what factors are affecting your tyre pressure levels when you’re inflating them. Some of the influencing factors include:

•        Ambient temperatures
•        Tyre temperature
•        Exposure to sun
•        Leakage (due to punctures or naturally leakage)

Know your recommended tyre pressure level

Vehicle manufacturers always provide a recommended tyre pressure, and this can be found either printed on a plate inside your B pillar (which you will see when you open the front doors) or in the user manual. Alternatively, there are some useful websites which provide recommended air pressures when you enter your vehicle registration. Either way, knowing the recommended tyre pressure is the first thing you should do before topping up underinflated tyres.

“Recommended temperature levels are cold inflation pressures”

It is important to be aware that the recommended pressure level provided is a cold inflation pressure, which means it’s the pressure level the tyres should reach when the temperature is cold. This poses a problem for those who do not have an air compressor at home. If you need to drive to the petrol station forecourt to use an air compressor, your tyres will likely be warm by the time you get there.  If you do drive to a garage forecourt to inflate your tyres, you can compensate slightly by inflating to a pressure level slightly above the recommended level, knowing that the pressure inside will decrease as the temperature cools.

The tyre pressure and the performance of your tyres will naturally fluctuate throughout the course of the day and in different conditions. When the external temperature is colder, tyre pressures will be lower, which will increase the amount of friction between your tyres and the road, as well as fuel consumption. Reduced pressure also makes the tyre sidewalls more flexible, resulting in worsened grip and handling. The increased friction also leads to increased heat build-up on the rubber surface of the tyre, which decreases it’s life.  A reduction of heat by just 1 degree Celsius results in a tyre pressure reduction of approximately 0.19 PSI.

Exposure to direct sunlight can also cause substantial fluctuations in tyre pressure levels, although less in the UK than in warmer climates. The impact of the direct sunlight can fluctuate tyre pressures by up to 15%.

How to minimise the effect of temperature change on tyre pressure

While it is not possible to constantly monitor the various factors that impact your tyre pressure levels, you can reduce the effects by regularly checking your tyre pressure on a monthly basis, and normalise the pressure levels relative to the ambient temperature at that time of year.

James
James has been a car mechanic by trade for more than eight years, and now focuses on sharing his knowledge and experience with others.