Ever wondered how much air your tyres need or what the letters and numbers around the sidewall of each tyre are there for?

All cars have a tyre placard with information about recommended tyre specifications and tyre inflation pressures for your car. Your tyre placard could be in your glove box, the driver’s door, inside the fuel cap or under the bonnet. The details are also in your car’s manual.

Or go straight to the source and check the information printed on the sidewall of your tyres.

 

Your tyre placard

 

On this placard you’ll find the correct pressure for the tyres originally fitted to your car. It shows:

  • Minimum allowable cold pressures
  • Pressure in Kilopascals (kPa) and often in pounds per square inch (PSI). The conversion is 7kPA = 1PSI
Tyre placard
Your car's tyre placard will be fixed somewhere to the vehicle

Only inflate your tyres to the maximum numbers shown on the placard. To get an accurate tyre pressure reading check them with a pressure gauge before you drive when they are cold or with the air pump at a nearby service station – only drive a short distance before checking them.

Get into the habit of checking tyre pressure every two weeks. If you notice a drop in pressure, especially in one tyre, it’s worth getting it checked for a puncture or defective valve. And don’t forget to replace the dust caps after you’ve checked them.

If you’ll be carrying an increased load or driving at high speed it’s a good idea to increase your tyre pressure, but never past the maximum pressures.

 


Understanding tyre markings

Your tyres have a lot of useful information printed on the sidewall about the type of tyre, loadings and tyre dimensions. Here’s how to read the markings on your tyre:

Typical markings on a tyre sidewall
Your tyre's sidewall contains lots of useful information

A – The brand, make and model of the tyre.

B – These three numbers show the tyre width in millimetres. This is the total inflated width at its widest point (excluding sidewall ribs and lettering). The ‘P’ indicates this is a passenger car tyre.

C – This number shows the height of the tyre as a percentage of the section width (B). This P205/60 tyre shows the section width is 205mm and the height is 60 per cent of that. The lower this number, the lower the tyre profile.

D – This letter shows the type of construction. R stands for radial, B for Bias.

E – This number represents the rim diameter which fits the tyre. This measurement is always in inches.

F – This number is checked against a chart to identify the maximum load the tyre can carry at the speed indicated.

G – This letter represents the maximum safety speed. Passenger tyre speed ratings start at N (140km/h) and go to Y (300km/h).

Last updated September 2018

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