Operation of commercial vehicles is inextricably linked with constant monitoring of the technical condition of the machine, and one of the key parameters here is the pressure in the tires. For a truck with a weight of tens of tons, even a slight deviation from the norm can lead to serious consequences, including increased fuel consumption, uneven tread wear and, most dangerously, the risk of sudden tire rupture at high speed. Many drivers and logisticians underestimate the importance of regular checks, relying only on visual inspection. visualization Often it is not able to detect a pressure loss of 20-30%, which is already critical for the rubber life.
Modern tire production technologies allow creating universal models, but they do not cancel the physical laws: the correct distribution of the load on the contact spot is possible only with strict adherence to the manufacturer's recommendations. TPMS systemsThe new tractors are designed to simplify the life of the driver, but they also require calibration and understanding of basic principles of operation. In this article, we will discuss in detail how air temperature affects the pressure gauge readings, why seasonal variations cannot be ignored and how to correctly calculate the necessary pressure for a particular type of cargo.
It is worth noting that saving on quality maintenance of the wheel pair often costs more than timely pumping. Losing just 10% of nominal pressure increases fuel consumption by about 1-2%, which in terms of annual truck mileage translates into significant financial losses. In addition, the under-performed tire operates in the mode of increased deformation of the sidewall, which leads to overheating of the cord and potential destruction of the frame. A critical threshold is a pressure reduction below 1.6 bar for standard cargo axles when the risk of aquaplaning increases many times over.
Impact of pressure on transport safety and economics
Safety on the road for a multi-ton car is not just an abstract concept, but a set of physical parameters that provide traction. At insufficient pressure, the contact spot increases, but the distribution of the load becomes uneven: the main mass falls on the shoulder zones of the tread, and the center does not actually work. This leads to the fact that brakeway increases, and the exchange rate stability decreases, which is especially dangerous when maneuvering or moving on wet roads.
From an economic point of view, the consequences are also deplorable. The pumped tire, although it has less rolling resistance, transmits all vibrations to the suspension and load, and also wears out faster in the center of the tread. The under-inflated tire “floats”, creating additional resistance, which the engine must overcome, burning excess diesel fuel. In commercial transportation, where margins often depend on litres per 100 kilometres, control is required. pneumosystem The wheels become a tool for direct cost optimization.
It is also important to consider the impact on the wheel design itself. Excessive pressure can cause the side to rupture or deform the disc when it hits the pit, as the tire becomes too rigid and stops cushioning the impacts. In contrast, low pressure contributes to increased heat, which can lead to rubber stratification and tread detachment. Regular monitoring allows you to avoid emergency situations and extend the life of expensive components.
Factors affecting performance in the tyre
The main factor to consider when measuring is temperature. According to the laws of physics, as the temperature of the air inside the tire increases, its pressure increases. This is why manufacturers always specify the rules for cold-tyreThose who have stood motionless for at least 3-4 hours or traveled less than 2 kilometers at low speed. If you check the pressure immediately after a long parking in the scorching sun or after the track, the gauge readings will be much higher than the real one.
⚠️ Warning: Never blow air from heated tires to bring the pressure back to normal! After cooling, the pressure will fall below the critical minimum, which will lead to overheating and destruction of the frame on the next flight.
In addition to temperature, the indicators are affected by the type of load and axis configuration. On the dual wheels of the rear cart, the pressure must be strictly the same, otherwise one wheel will take on most of the weight, operating in extreme mode. Height is also worth considering, although for most freight traffic within the continent, this factor does not play a decisive role in comparison with the temperature regime and weight of the cargo.
Check the pressure always under the same conditions, preferably in the morning before the start of movement, when the tires are guaranteed to be cold and at rest.
Table of pressure standards for different axles and loads
There is no universal number for all trucks, as each tire and wheel manufacturer sets its own limits. However, there are generally accepted standards that most carriers are guided by. Below is a table with indicative values for standard tyres of standard size. 315/70 R22.5which are most common on the main tractors.
| Axle/Wheel type | Load (kg per wheel) | Pressure (bar) | Recommendation |
|---|---|---|---|
| Steering axle (single) | 3,000 | 8.5 - 9.0 | Strictly on the body sticker |
| Drive axle (twin) | up to 2,500 | 8.0 - 8.5 | Same on all 4 wheels |
| Trailer (twin) | up to 2700 | 9.0 - 9.5 | Control every 2 days |
| Full loading. | Maximum | 9.0 - 10.0 | Do not exceed the MAX on the sidewall |
It is important to understand that the data in the table are averaged. The exact values for your particular car can always be found on the information sticker, which is usually located on the inside of the cabin door or on the center rack. Ignoring this data and pumping "to the general standard" may result in the warranty being cancelled in the event of damage to the tires.
Always check the factory plate on the car, and not only with the marking on the sidewall of the tire, since the vehicle manufacturer has already taken into account the features of the suspension and weighting.
Seasonal features and temperature correction
The change of season is the period when wheel control needs to be tightened. In winter, with a sharp cooling, tire pressure drops by about 0.1 bar for every 8-10 degrees of temperature drop. If you pumped the wheels in the fall at +10 ° C, and hit the frost in -20 ° C, the pressure loss can be more than 3 bar, which is a critical indicator. The driver must be pre-empted temperature-compensation, pumping tires slightly above normal before the onset of cold weather, but not exceeding the limit values.
In summer, the situation is reversed: heating from the sun and friction on the asphalt causes pressure to rise. It is important not to pump tires here, as hot asphalt combined with high internal pressure can trigger an explosion, especially on old or refurbished tires. Experienced truckers know that after a long parking in the sun, the gauge indicators can "jump", so it is better to check in the shade or in the morning.
Using nitrogen instead of conventional air in truck tires is a controversial topic. Nitrogen is less prone to temperature expansions and penetrates through rubber micropores more slowly, which provides more stable pressure. However, if you don’t have the ability to use nitrogen all the time, it’s better to top up normal air than to drive with under-performed wheels.
Does nitrogen really prevent the disk from rotting?
Yeah, that's partly true. In ordinary air contains moisture and oxygen, which contribute to the oxidation of the metal cord and the inner surface of the disc. Nitrogen is an inert gas, it is dry and does not support oxidative processes, which prolongs the life of the wheel from the inside.
Monitoring tools and measurement accuracy
For accurate determination of pressure in cargo tires, where values reach 8-12 atmospheres, conventional passenger gauges are not suitable - they either lie on such values, or have too small a scale of division. Specialized services should be used loader with a measurement range of 16-20 bar. Digital instruments provide high accuracy, but mechanical hand-held models often prove more reliable in harsh operating conditions and do not require batteries.
When choosing a tool, pay attention to the accuracy class and the presence of a protective housing. Falling the pressure gauge on the concrete floor of the fleet should not disable it. Also a convenient solution are the Automatic Tire Inflating Systems (CTIS), which allow the driver to adjust the pressure directly from the cabin, which is especially useful when driving on off-road or soft ground where a reduction in pressure is required to increase the contact spot.
- 🛠️ Mechanical gauge: It is reliable, not afraid of frost, but requires regular calibration and careful handling.
- 📱 Digital pressure gauge: convenient illumination, high accuracy, but depends on the battery charge and can "glutch" at extremely low temperatures.
- 📡 The TPMS system: transmits real-time data, warns of punctures, but requires replacement of sensors and settings.
☑️ Checking the pressure gauge before use
Typical errors in the maintenance of wheels
One of the most common mistakes is to ignite the caps on the discs. In winter, moisture trapped inside the cap freezes and blocks access to the nipple, and can also cause corrosion. Drivers often forget to remove their caps before checking, which leads to incorrect readings or inability to pump the wheel. In addition, many people use the eye or kick the tire, which is completely uninformative for a high-pressure freight wheel.
⚠️ Note: The use of sealants to eliminate punctures in cargo tires is permissible only as a temporary measure. The residues of the sealant can disrupt the wheel's balancing and damage the TPMS pressure sensors.
Another mistake is ignoring the state of the nipple spool. Mud and dust stuffed inside, do not allow tightly twist the cap or connect the compressor hose, which leads to air leaks. Regular replacement of caps with new ones, preferably with a rubber seal, helps to keep the pressure stable for a long time.
Do not forget about the visual inspection of the sidewalls for cuts, hernias and protruding cord. Pressure is an important, but not the only, parameter of tire health. Cracks on aging rubber can cause sudden depressurization even at ideal internal pressure.
Can different manufacturers mix tires on the same axle?
It's not recommended. Different tread pattern and rubber mixture composition lead to different coefficient of adhesion and wear rate. This causes an uneven load on the differential and can lead to the skidding of the road train.
What if the pressure is constantly falling in one wheel?
If you notice that one tire pressure drops faster than the others, you need to conduct a diagnosis. First, check the nipple spool, dripping soapy water on it - the appearance of bubbles will indicate a leak. If the spool is intact, examine the disc for corrosion around the rim (often after winter with reagents). The third option is a micro-puncture, which can be found in a bathtub with water or by ear. Ignoring the constant loss of pressure will cause the tire to fail.
Does the pressure in the trailer tires affect the wear of the tractor?
Yeah, it's indirectly. If the trailer under-pumped wheels, the rolling resistance of the entire train increases. The tractor engine is forced to work with increased load to pull the "heavy" trailer, which leads to an increase in fuel consumption and engine temperature. In addition, the instability of the trailer due to bad tires can be transmitted to the saddle device and the tractor frame.
How often should I change the pressure gauge?
Professional pressure gauges require verification or replacement approximately every 1-2 years of active use. If the device is dropped, or the arrow "sticks" and does not return to zero, its use is unacceptable. Accuracy of testimony is the key to safety and saving money.