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A Guide to Tyre Pressure Monitoring Systems (TPMS)

Last updated : January 2, 2025
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Audio - A guide to TPMS and July 2024 EU regulations
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Proper tyre inflation is critical for the safety and performance of fleet vehicles, making tyre pressure monitoring systems (TPMS) an indispensable feature. But what is TPMS exactly, how does it work, and why is it important?

In this guide, we’ll cover all the details of TPMS while providing you with essential insights to navigate EU TPMS regulations so that you can guarantee compliance with the standards and thereby optimise your fleet operations.

What is TPMS?

TPMS, an abbreviation for tyre pressure monitoring system, tracks the tyre pressure levels of a vehicle and promptly alerts drivers when a significant deviation or imbalance occurs. As such, these systems are vital for maintaining optimal tyre conditions, effectively averting blowouts, a common cause of on-road accidents.

How does TPMS Work?

Fundamentally, TPMS operates via compact electric sensors which are installed onto each wheel of a vehicle. From there they measure tyre pressure before transmitting this data, presenting a dashboard warning if it has dropped below a certain point. However, it's notable that TPMS comes in two distinct types: direct and indirect.

How does Direct TPMS Work?

Direct TPMS works through air pressure sensors situated on each wheel's valve which actively monitor tyre pressure. These sensors typically offer real-time readings for tyre pressure and temperature. Subsequently, the system wirelessly sends this data to the vehicle, triggering a dashboard alert in case of pressure fluctuations.

Advantages and Disadvantages of Direct TPMS

Direct TPMS provides more accurate tyre pressure readings, eliminating the need for recalibration after tyre inflation or rotation. Additionally, its sensor batteries tend to have a longer lifespan, making it more reliable. Although, these sensors are more susceptible to damage during tyre changes, and the system itself tends to be more costly compared to indirect TPMS.

How does Indirect TPMS Work?

Indirect TPMS avoids air pressure sensors within the tyres. Instead, these systems rely on ABS wheel speed sensors to detect pressure loss. By analysing relative wheel speeds, the system generates pressure readings and compares them across all four tyres. The underlying concept is that an under-inflated tyre rotates at a faster pace than expected, triggering a dashboard alert.

Advantages and Disadvantages of Indirect TPMS

Indirect TPMS presents a more economical alternative to direct TPMS and demands less frequent calibration. On the other hand, it necessitates resetting after tyre maintenance and does not provide precise pressure readings. For instance, slight variations in tyre sizes may lead to incorrect measurements.

Does TPMS Replace Manual Tyre Checks?

Although TPMS provides alerts for substantial drops in tyre pressure, it is not a substitute for regular manual inspections. Fleet drivers should routinely check each tyre using a reliable pressure gauge to confirm it is properly inflated and inspect the tread depth to make sure it meets safety standards.

Likewise, manual vehicle checks are still worth doing to account for potential technological faults and to verify tyre pressure accuracy. Even slight deviations from the recommended pressure can result in tyre damage, reduced fuel efficiency, shortened tread life, as well as poor braking, cornering, and handling.

Can You Drive with the TPMS Light On?

When the tyre pressure warning light activates, it means that the air pressure in one or more tyres has dropped below the acceptable threshold. This could be due to a puncture, damage, or other issues.

For example, in some cases, sudden changes in temperature, such as moving from a cold environment to a warm one, can trigger alerts in direct TPMS systems until the temperature stabilises. Similarly, indirect TPMS systems might occasionally misinterpret uneven tyre wear as a pressure fluctuation.

Regardless of the cause, ignoring the TPMS light can compromise fleet safety, so it’s best to take immediate action if the warning light appears. Do this by pulling over to a safe location before visually inspecting the tyres. If any look deflated but show no signs of damage, re-inflate them to the suitable pressure. After doing so, driving for a short distance or restarting the vehicle may reset the TPMS system and turn off the warning light.

Is TPMS A Legal Requirement?

TPMS became a legal requirement for new passenger vehicles in the EU starting in November 2014. The shift began on 1 November 2012, when legislation required all new car models sold in the EU to include TPMS. 

This mandate expanded in November 2014 to cover all new passenger vehicles sold. In the UK, further legislation came into effect on 1 January 2015, stipulating that vehicles with a faulty or inoperative TPMS sensor would fail their MOT test.

TPMS Regulations for Trucks and Trailers

Initially, legislation requiring TPMS applied exclusively to M1 vehicles - those designed to carry passengers and featuring no more than eight seats in addition to the driver’s seat. Yet, recent updates have expanded this mandate to include N1 vehicles, which are designed for transporting goods and have a maximum mass not exceeding 3.5 tonnes. 

Additionally, TPMS fitment is now also mandatory for other vehicle categories including M2, M3, N2, N3, O3, and O4. This concerns all trailers within the EU under the UN ECE R-141, a key provision of the EU’s Vehicle General Safety Regulation. This legislation primarily aims to increase road safety for all while cutting down on unnecessary fuel wastage. 

TPMS regulations represent a proactive stride toward the future of fleet safety. Specifically, they work to mitigate the risk of tyre-related incidents and closely align with the transport sector's current sustainability objectives.

TPMS Servicing and Maintenance

Over time, the internal battery of a direct TPMS sensor will deplete, calling for replacement of the sensor. Moreover, sensors might fail or become faulty down to factors such as weather exposure, corrosion, or accidental damage.

To ensure the TPMS system functions correctly and to avoid an MOT failure, routine servicing is important. This often involves the use of specialist diagnostic equipment to inspect and maintain the system. Many manufacturers also recommend replacing the valve cap and core components every time a tyre is changed to prevent issues.

Essentially, regular TPMS servicing extends the sensor's lifespan, prevents corrosion in the valve, and guarantees an airtight seal. That said, indirect TPMS systems, which estimate tyre pressure through wheel rotation data, do not need battery replacements or valve servicing. Albeit, these systems may need recalibration when tyres are inflated, rotated, or replaced.

Why is TPMS Important?

TPMS holds paramount importance due to underinflated tyres in commercial vehicles being a stark precursor to serious accidents. Its single purpose is to avert such incidents by facilitating proper tyre maintenance.

Having said this, TPMS also contributes value to overall fleet management efforts by delivering:

  • Enhanced Safety: Optimal tyre pressure supports the safety and manoeuvrability of trucks and trailers, thereby enhancing road safety for drivers and other road users alike.

  • Cost Reduction: Keeping tyres in optimal condition minimises unplanned downtime, translating to tangible cost savings.

  • Decreased Fuel Consumption: Properly inflated tyres yield improved fuel efficiency, leading to decreased expenses and reduced CO2 emissions.

  • Extended Tyre Lifespan: Consistently maintaining correct tyre pressures prolongs their longevity, lowering the frequency of replacements and associated expenses.

Benefit from TPMS with MICHELIN Connected Fleet

In essence, TPMS not only safeguards against accidents but also yields very real benefits in terms of safety, cost-efficiency, and environmental sustainability within fleet management operations. 

And so, while regulations might initially elicit a negative reaction, failing to ensure compliance with TPMS requirements will actually place your fleet at a severe disadvantage.

Recognising the pivotal role of TPMS, we at MICHELIN Connected Fleet have developed our own innovative solutions which empower fleet managers by providing real-time alerts for dangerously low tyre pressures alongside set temperature thresholds to identify when service interventions are needed.

If you're interested in mitigating major breakdowns, reducing costly repairs, minimising unscheduled downtime, curtailing excessive fuel consumption, and upholding regulatory compliance, then be sure to make an enquiry into our services today.
MICHELIN Connected Fleet

Written by MICHELIN Connected Fleet

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