We will tackle an essential element for vehicles: tire pressure. These explanations are mainly for new drivers and those who want to know more about their vehicle.
What is the correct pressure for a tire?
The maximum recommended pressure is indicated by the manufacturer on the tire based on a multitude of tests. The pressure is always given for cold tires. The manufacturer gives two indications, the pressure in normal use and the pressure when the vehicle is loaded. This one is a little superior to the first one. It is indicated in bar kg / cm², or kilopascals and in PSI (pounds per square inch), it is the English measure. Often the optimal pressure differs between the front and rear tires.
Step one: Find the recommended pressure.
This one can be the same for the four tires or to be differentiated between those of front and those back. It will depend on the car model.
We find this information on the tire itself but in this case it is the maximum pressure, which does not mean the best. Generally it is between 195 and 250 kilopascals or 28 to 36 PSI.
The optimum pressure can be found in the vehicle maintenance guide, or on a label stuck in the driver's side door or on the back of the fuel tank or diesel valve.
Second step: Check the pressure when the tire is cold.
We check the pressure when the tires are cold, they must not have been used for 2 hours. That's why it's best to check this pressure at home rather than at the gas pump. There are portable or static compressors that you can buy to do this check at home.
Indeed, the hot air is more dilated and will distort the result. When the tires cool down the pressure decreases. If measured hot, there is a risk of under-inflating the tires which will lead to abnormal wear thereof.
1. Removal of the cap
All tires have a valve, often made of black rubber, sometimes it is silver. This valve is covered with a black or silver cap for certain vehicles. This plug is important, it prevents dust and dirt from clogging the valve. Of course, to check the pressure it must be removed.
2. Placement of the gauge
So either you have a compressor with an included gauge allowing you to measure the pressure (most portable compressors of our day have one) or you will have to place a gauge that only serves to measure the pressure.
The tip of the compressor or gauge is placed against the valve. If you press the stem in the center of the valve, you will hear a whistling sound, it is the air coming out under pressure.
When the compressor is properly placed the hissing stops, sign of a tight connection between it and the tire. The indications of the gauge will then be correct.
3. Reading the pressure
On the dial gauge you can read the actual pressure in the tire and see if they are underinflated (too much pressure) or over-inflated (pressure too high) compared to the recommendations of the manufacturer.