The tyre is the only component in contact with both the vehicle and ground, therefore proper inflation pressures are mandatory to provide safe operation and maximize the tyre lifetime and tyre efficiency.


As the compressed air in the tyre supports the load, an incorrect pressure, whether associated with overinflation or underinflation may cause tyre failure. Excessive casing stress with overinflated tyres, or increased flexing and an excessive amount of heat with under-inflated tyres, are the main consequences. A correct tyre pressure, by ensuring the optimal contact between the tread and the road, guarantees the tyre even wear.

Pressure must be measured only when the tyre is cold. The spare tyre must be check as well. Make sure that the valve cap is always properly screwed.

Don’t “Bleed” the Tyres

The so-called tyre bleeding is the practice of reducing the pressure of tyres, which have run, warmed up, and, therefore, have higher pressure vs. their cold measurement. During the operation, all tyres generate heat that expands the inflation air and causes a wrong pressure measurement.

Checks must be conducted before driving when the tyres are still at ambient temperature. If tyre pressure is checked when the tyres are warm or hot, the pressure will be significantly higher providing a not correct measure. Therefore, do not deflate a hot tyre after a pressure measurement: most likely your tyre will end underinflated!

The tyre pressure, determined with cold measurement, must be adjusted according to the service parameters: load, speed, and conditions of use. Proper air pressure is the key to secure the correct tyre footprint for a given load minimizing the risk of irregular wear.

Recommended Frequency For Pressure Checks

Tyre pressure should be checked frequently, including the spare tyres. The table below provides guidelines according to the different tyre types and service conditions.

≤ 8.000 km/month
> 8.000 km/month
ON/OFF 1 7 10 15
≤ 100 km radius of activity
> 100 km radius of activity
PURE OFF 1 7 10 15
≤ 1 shift (building sites)
> 1 shift (building sites)

If the tyre pressure is checked in low-temperature conditions (e.g. winter), the pressure will be lower than in normal temperature conditions. In cold conditions, it is recommended to increase the frequency of the tyre pressure checks.

Under Inflation

under inflation

A tyre that is underinflated causes the casing ply to over flex. This over flexing can lead to a rupture of the casing ply and subsequent rapid air loss. This condition is commonly referred to as a zipper rupture.

Any tyre with a pressure of 4 psi/0,28bar or lower, should be checked thoroughly for penetrations, valve leakage, or wheel damage which may account for the pressure loss.

Any tyre that has run 20% below the recommended pressure should be considered flat. The tyre should be removed and demounted for a complete inspection of the interior. If signs of run-flat damage are present, the tyre should be scrapped.

Over Inflation

over inflation

The main consequence of over inflation on Truck & Bus tyres is the excessive cable tension which increases the probability and severity of fatigue and impact damage to the casing.

Prolonged operation of overinflated tyres will cause irreversible degradation and can result in an unpredictable rapid air loss condition.

over inflation graph

Impact of Inflation Pressure on Tyre Performance

No tyre or tube is completely impervious to the loss of air pressure. To avoid the hazards of under inflation, lost air must be replaced. Inflation pressure has a direct impact on tyre performance, both tread life and endurance, as shown in the following charts.

Pressure Effects on Tread Life
Pressure Effects on Casing Life
correct pressure
20% under inflation
20% overload

WARNING: Driving on any tyre that does not have the correct inflation pressure is dangerous and will cause tyre damage. Any under inflated tyre builds up excessive heat that may result in sudden tyre destruction. Pressures that are too high can lead to more rapid and uneven wear as well as being more vulnerable to road hazard damage. Consult an Aeolus tyre dealer or Technical Data Book for the proper inflation pressures for your application.

All Aeolus tyres correspond to the provisions and guidelines of each country. For more information read the standards and regulations of your country.