The TPMS (Tyre Pressure Monitoring System) allows you to detect when your tyres are too low in pressure. It has been compulsory in Europe since 1 November 2014 (in the USA since 2007), which means that your vehicle is equipped with it if it was manufactured after this date.
In practical terms, TPMS is able to display your tyre pressure level on your dashboard via an indicator or warning light.
How does tyre pressure sensor work?
The TPMS can operate on two detection systems: direct and indirect.
With the direct system, pressure information is fed back in real time via a tyre pressure sensor in the tyre or valve. It is sent to the on-board computer to present the information on your dashboard. Depending on your vehicle, it can take a different form:
A warning light or signal light
Pressure level of your tyres
With the indirect system, the tyre pressure is calculated by the Tyre Pressure Monitoring System on the basis of the wheel rotation speed, which is also used by the ABS (Anti-lock Braking System) and ESP (Electronic Stability Program).
The speed of rotation increases when the diameter of the wheel is reduced due to under-inflation. The information is then sent to the dashboard by the TPMS.
TPMS: advantages and disadvantages
The advantage of this system is that it provides an automatic warning of your tyre pressure. You might then think that you don't have to go to the service station every month because the TPMS is there to tell you when it's time to reinflate your tyres. But that's not what we recommend.
The TPMS has one drawback: it only activates when your tyres have lost 20% of their air, which is about 0.4 bar on average.
Why is this a problem?
Because it is considered that at this pressure level the tyre is already under-inflated and it is known that an under-inflated tyre leads to premature wear. If your tyre wears out prematurely, it will have to be replaced earlier than expected. That means extra costs.
As handy as this indicator is, it is still recommended to check your tyre pressure once a month to avoid having to replace your tyres prematurely.
How to set the TPMS?
You don't have to do anything special because the warning system has been set to the optimum pressure for your tyres. When one of your tyres is under-inflated (i.e. when its pressure is less than 20% of its recommended pressure), a light on your dashboard will appear. This is your TPMS indicating which tyre on your vehicle is affected.
When should the TPMS be recalibrated?
If you choose a different tyre size, it is possible that the recommended pressure is different from the original tyre.
In this case, a professional will have to re-set the TPMS so that it alerts you to any drop in pressure related to this new configuration.
Tyre pressure sensor replacement
Although the theoretical life span of tyre pressure sensors is 5-7 years.
That’s because tyre pressure sensors are exposed to corrosion, shocks and high speeds when driving on the motorway.
In the event of a malfunction, you can contact a professional to have the defective tyre pressure sensor replaced.