Other tips and advice
Tyre pressure for cars
Tyre pressure for cars
A tyre loses some of its pressure naturally (typically around 1 psi (0.076 bars) per month). Pressure loss may be accelerated by other air leaks due to:
• an accidental puncture
• the valve: which must be changed each time a tyre is changed.
• the valve cap: essential to guarantee an airtight seal.
• the wheel: which should be cleaned each time a tyre is fitted.
• Follow the vehicle or tyre manufacturer's advice, particularly with regards to conditions of use (loads/speeds, etc.).
• Check pressures when the tyres are cold (tyres which have not been used in the last 3 hours or have covered less than 2 miles (3 km) at low speed).
• If tyres are hot when they are checked, add 4 to 5 psi (0.3 bar) to the pressure recommended by the vehicle manufacturer. Re-check the pressures when the tyres are cold.
• Never deflate a hot tyre.
• Even if tyres are inflated with nitrogen, the pressures and overall tyre condition must still be checked frequently.
A correctly inflated tyre improves safety, is more economical in use and is better for the environment.
How do I check my tyre pressure?
- Insert the pressure gauge into the valve stem on your tyre.
- The gauge will “pop” out and show a number that corresponds to the internal pressure in the psi number.
- The hissing sound is air escaping the tyre. It shouldn’t affect pressure substantially, unless you hold down the air-pressure gauge for too long.
- Compare the measured psi to the recommended psi.
If the psi is above the recommended number, let air out until they match. If it's below, add air until it reaches the right number.
Where can I find the recommended pressure for my tyres?
- In the vehicle owner's manual.
- On a sticker in the driver's or passenger's door, or the fuel tank door.
- Do not use the number on your tyre’s sidewall, as this does not indicate the pressure needed in your tyre.
About pressure gauges
- Be careful if you are using a pressure gauge provided in a service station. These pressure gauges are often unreliable.
- Buy a high-quality pressure gauge and check its accuracy with a tyre professional.
Getting it right is important
Under-inflated or over-inflated tyres can wear down faster than expected, have reduced grip, and can consume more fuel. It just takes a few minutes a month to help ensure your safety and the longevity of your tyres.
By keeping your tyres at their correct pressure, you’ll reduce your running costs. Under-inflated tyres are prone to overheating, use more fuel, and wear out more quickly. Likewise, over-inflation can reduce tyre life, reduce grip, and cause steering problems.
A 20% under-inflated tyre can cover 20% less mileage. That means a loss of 5,000 miles (8,000 km) on a potential mileage of 25,000 miles (40,000 km).
• FUEL CONSUMPTION AND CO2 EMISSIONS.
Low tyre pressure increases both fuel consumption and CO2 emissions.
Nitrogen: What are the benefits?
What is nitrogen?
Nitrogen is simply dry air with the oxygen removed. Air contains nearly 79% nitrogen.
How is it used?
- Most tyres are filled with compressed air. But some tyre retailers have started to put nitrogen into their tyres.
- Nitrogen and compressed air can be mixed.
- Most tyres can be inflated with air or nitrogen, as long as the pressures recommended by the vehicle manufacturer are respected.
When nitrogen replaces oxygen, less air can escape from your tyres, and your inflation pressure stays higher, longer.
Unfortunately, there are other possible causes of leaks (tyre/rim interface, valve, valve/rim interface and the wheel), so there's no guarantee of maintained pressure with either air or nitrogen. The pressure and overall tyre condition must still be checked frequently.
Valve: What should I know?
What is the role of the valve?
It ensures that the proper tyre pressure is maintained.
It blocks moisture from entering the tyre.
The valve cap is particularly important to help block dust particles from obstructing the valve. High-quality caps are recommended.
Ageing and damage
Valves are usually made of rubber and therefore age with time.
They can be damaged by high speeds causing air to leak from your tyres.
When should I change the valves?
Whenever you buy new tyres.