How do tyre pressure monitoring systems work?
You may have heard about TPMS or noticed a light in your car that signals this, but do you know what it is and how it works? A Tyre pressure monitoring system (TPMS) is an electronic system that monitors the air pressure in your tyres and is found inside them. If your tyres are over or under-inflated, the TPMS will be activated and a warning light will appear on your dashboard. This occurs when your tyres are around 10% below the recommended tyre pressure.
There are two different types of TPMS; direct and indirect. When the warning light on your dashboard appears, this is the final step in the process of either of these.
Indirect TPMS
This relies on the tyre speed sensors that the anti-clock brake system also uses. The indirect TPMS measures the rate of revolutions each wheel makes and is used by computer systems on your vehicle to compare with other data like speed.
As each wheel is conducted, the computer is able to interpret the relative size of the tyres on the vehicle. If your wheel begins to spin faster than usual, the computer will understand that the tyre is being underinflated, which is when the warning light on your dashboard will appear.
An indirect TPMS doesn’t actually measure the pressure of your tyres. It is there to help measure the speed at which your tyres are rotating and then sends signals to the computer that will activate the warning light if something doesn’t look correct.
Direct TPMS
This system uses sensors located in each tyre that is able to monitor the actual pressure levels. The sensors used in TPMS can also provide motorists with tyre temperature readings. This system is able to send all the collected data to a central control module, which is where all data is examined and understood.
If the tyre pressure is lower than it should be, the warning light will flash on your dashboard. The majority of direct TPMS will send this data wirelessly. Every tyre sensor has a unique number which is helpful when they need to be distinguished from other pressure readings taken from other vehicle systems, as well as other tyres on your own car.
If you’re looking to get your current system replaced with a direct TPMS, you’ll need an experienced technician to do this for you.
Both TPMS systems serve the same purpose and work to activate the same warning light if needed. These systems are capable of delivering very accurate readings and alerts if they need to, however, they should not be considered as a replacement for manual air pressure checks. You should still continue to monitor your tyres and regularly check the air pressure.