Helpful car tips – Tire air pressure: the most important things at a glance

contents

• Why is correct tire air pressure so important?
• Determine the correct tire pressure
• Insufficient air pressure in the tires – these are the consequences
• Air pressure in car tires is too high – these are the consequences
• Check tire air pressure: Here’s how
• TPMS: This is what automatic tire pressure monitoring systems can do
• Conclusion

Why is correct tire air pressure so important?

The entire weight of the car, including passengers and load, rests on the car tires. The supporting element is – air. If there is too little of it in the tyre, it will wear out quickly and increase fuel consumption. If the pressure is too high, there is a risk of losing traction. As you can see, it is essential that the air pressure in the tire is correct. The general recommendation for cars is around 2.5 bar. However, the value cannot be fixed as a flat rate, but depends on several factors:

• manufacturer and vehicle
• number of passengers
• loading of the vehicle

Basically, the air pressure can be increased slightly for longer car journeys, when the vehicle is fully laden or on uneven roads.

Depending on factors such as the surface, the air pressure in the car tires should also be set correctly.

Determine the correct tire pressure

Before you check tire pressure, you should find out what pressure is recommended for the tire on the specific vehicle. In addition, the values ​​for both summer and winter tires often vary slightly for the front and rear wheels. The automobile manufacturers attach stickers to the vehicles that provide information about the tire air pressure at average and at full load. You can usually find these labels

• on the B-pillar when the driver’s door is open
• in the glove compartment
• in the tank cap.

In addition, technical data on tire pressure can be found in the logbook or in the car’s operating instructions. Almost all automobile manufacturers and tire producers also publish tire pressure tables with detailed information on the Internet.

Important is: The information on the air pressure in the tires always refers to cold tires. Consequently, the tire pressure should be checked after the vehicle has been parked for a sufficiently long period of time. If the car has already been driven a number of kilometers and the air pressure according to the table is only then filled in, this is generally too low.

Insufficient air pressure in the tires – these are the consequences

If a tire is under-inflated, the tread bulges inwards and only touches the road with your shoulders. As a result, the entire central sector of the tread no longer has any contact with the road. The following consequences can occur:

• loss of traction: The tires spin when accelerating because the contact on the edges is too small to transfer the power to the road.
• Extension of the braking distance: The tire can no longer transmit the braking forces, which means that the braking distance increases significantly.
• Low driving stability: If the tires of a car have significantly different air pressures, it is difficult to keep the vehicle on track. In the event of emergency braking, the car may swerve.
• Danger of aquaplaning: Silicate or carbon particles are often incorporated into the tread of all-weather tires and winter tires. These components act like claws that get stuck firmly in the road. These innovations ensure optimum grip, especially on snow and wet roads. If the air pressure in the tire is too low, these little claws can no longer straighten up. In extreme cases, the entire system can become inoperable.
• High tire wear: Due to the increased friction at the edges of the tread, the tires wear out unevenly and much faster.
• Risk of tire overheating: Due to the increased friction, the tire can heat up considerably and, in the worst case, the tire can burst.
• Increased fuel consumption and emissions: The rolling resistance increases, so that more fuel is consumed when driving.

Air pressure in car tires is too high – these are the consequences

Some motorists increase the air pressure in their tires above the manufacturer’s recommended pressure in order to save fuel. There is nothing wrong with that, as long as the recommended pressure according to the tire pressure table is exceeded by a maximum of 0.3 bar. But beware: You should not increase the tire pressure any further. While driving, the tires heat up, causing the pressure to rise even more.

If the tire air pressure is too high, the tread bulges outwards and the tire only touches the road in the middle. This can have different consequences:

• Extended braking distance: The braking force cannot be transmitted, which means that the braking distance is measurably longer. There is a risk of a flat tire – even with moderate deceleration.
• Less cornering stability: When cornering, tires with excessive air pressure offer significantly less traction, which can sometimes be dangerous.
• Low traction: When accelerating, the tire spins because the contact surface of the profile, which is now too small, is not sufficient to optimally transfer the power to the road.
• tire overheating: Since all the friction takes place in a narrow area, the tire can become very hot due to the frictional forces. This expands the air in the tire, which is already too much, which can cause the tire to burst.
• High wear: The tire wears out in the middle of the tread very quickly and then has to be replaced.
• ABS limitations: The ABS sensors cannot take correct measurements, particularly if the air pressure in the tires is too high. This can cause the ABS to stop responding.
• damage to the vehicle: Due to the high pressure in the tire, it loses its cushioning properties. Shocks are passed on to the chassis almost unfiltered, which can lead to serious damage.

If the air pressure in a car tire is too low or too high, premature wear can result.

Check tire air pressure: Here’s how

You can usually find gauges at every gas station that you can use to check the tire pressure. If you travel a lot by car and often drive longer distances, then it might be worth getting a measuring device. Electronic and mechanical tire pressure gauges are available from tire dealers and car accessories. When buying, it is important that these measuring devices work accurately and are easy to use and read. Cheap models can rarely meet these requirements.

6 steps to check tire pressure:

1. Remove the end caps from the tire valve stems.
2. Insert the tire pressure gauge into the valve stem and quickly depress to get a reading.
3. Check the measured pressure and compare it with the recommended tire pressure.
4. If the reading is above the recommendation, push the valve in to release air.
5. If the reading is below the recommended value, inflate the tire to the recommended pressure.
6. Do this for all tires on the vehicle – including the spare tire! The spare tire can be filled with 0.5 bar above the recommended pressure.

Note: If you check the tire pressure in the garage in winter, you may get incorrect values, especially if the garage is heated. This also applies if the car has been standing in the blazing sun for a while before the measurement. It should be noted here that the tire pressure changes by around two percent for every 10° Celsius.

Is tire gas worth filling?

Workshops and tire dealers often offer tire gas as a filling. A filling with tire gas for four tires costs about ten euros – but the tires should not get hotter and lose hardly any pressure.

Tire gas is nothing more than nitrogen, around 78 percent of which is already contained in normal ambient air. Nitrogen absorbs heat less quickly, which is why this gas is ideal for filling tires. However, the tires on normal cars never get so hot that it is worth the effort. On the other hand, it makes sense to fill the tires of racing cars or airplanes with nitrogen, where there are significantly higher loads.

TPMS: This is what automatic tire pressure monitoring systems can do

Newly registered cars in the EU have had to be equipped with a tire pressure monitoring system (TPMS) since November 2014. These are intended to protect drivers from the consequences of incorrect air pressure on the tires. This control system usually takes direct measurements using sensors in the valve or in the tire. Another option is indirect measurement, in which every change in the rolling circumference of the tire is registered. If the TPMS gives a warning, you should check the tire pressure as soon as possible.

The advantage of these assistance systems is that you have a better view of the condition of the tires. In this way they contribute to safety – however, this is not a substitute for regular tire checks. For example, some warning systems only activate when the tire pressure falls 25 percent below the pressure recommended by the vehicle manufacturer. In practice, this means that a TPMS can warn of a flat tire, but not of a gradual loss of air or excessive tire pressure.

Conclusion: Lower fuel consumption, more safety, high mileage

It’s the air pressure that supports the car – not the tires. The correct tire pressure is therefore crucial for the handling of the vehicle. For this reason, you should check the tire pressure regularly, ideally every 14 days. This is rewarded in several ways: fuel consumption and emission values ​​are optimally low with the correct tire pressure and tire wear is reduced, while safety on the road is increased.