Understanding tyre pressure monitoring systems (TPMS)

A tyre pressure monitoring system is an electronic safety feature built into your vehicle that tracks the air pressure inside your tyres. Its main function is to warn you when the pressure in one or more tyres falls to a dangerously low level. The early warning helps prevent tyre blowouts, improves your car's fuel economy, and can extend the life of your tyres.

There are two main types of systems.

• Direct TPMS uses a dedicated tyre pressure sensor inside each wheel to measure air pressure directly. It sends real-time data to your vehicle's computer, providing accurate readings for each specific tyre.

• Indirect TPMS infers pressure loss using the anti-lock brake system's (ABS) sensors. It works by detecting differences in the rotational speed of your tyres. An underinflated tyre has a slightly smaller diameter, causing it to rotate faster than the others, which triggers a warning.

As you drive, the system constantly monitors your vehicle’s tyre pressure. When the pressure drops below a safe level, it signals an immediate alert. Tyres naturally lose around 1-2 psi a month, while plummeting temperatures in the colder months reduce tyre pressure by 1.5 PSI for every 10°C drop. Monitoring this also ensures optimal performance when you’re driving on narrow, winding rural roads or towing a trailer with an SUV or pickup truck.

Having a functional monitoring system offers several advantages for safety, savings, and overall performance.

Improved safety

Underinflated tyres are a significant contributor to blowouts and accidents because they overheat from excessive flexing. By providing an early warning, the system reduces this risk.

Better fuel efficiency

Driving on correctly inflated tyres can improve your fuel mileage.

Longer tyre life

Improper inflation leads to uneven and premature tread wear, wearing down the outer edges due to under-inflation or the centre of the tyre due to over-inflation. The system helps you maintain the correct pressure, preventing costly early replacements.

While these systems are reliable, they can have issues.

Battery failure

The battery inside a direct tyre pressure sensor lasts between five and ten years. When it fails, the entire sensor unit typically needs to be replaced because the battery is sealed.

Sensor damage

The sensors are located inside the wheel and can be damaged when you are changing your tyres or if a tyre hits a kerb too hard.

False alerts

A sudden cold snap can trigger a warning. If an alert appears, check your tyre pressure as soon as possible.

The best maintenance practice is to have a professional inspect the system during your regular tyre services.

Many new vehicles today come with a tyre pressure monitoring system fitted as standard. If you have an older vehicle, you can have an aftermarket system installed to gain the same safety benefits.

Whether you are replacing a faulty sensor or installing a new kit, the work should be carried out by a trained professional. Correct installation and calibration are essential for the system to function correctly and provide accurate warnings.

Ensuring your tyres are always at their recommended pressure is a key part of your safety, vehicle efficiency, and driving comfort. If you have a warning light or want to ensure your system is working correctly, visit a professional. Some Michelin-approved service centrese can perform expert tyre pressure checks, TPMS calibrations, and maintenance.