A tyre pressure monitoring system (TPMS) in vehicles utilizes electronics and sensors inside or outside the tyre to warn the driver of pressure loss in tyres.
TPMS consist of a low tyre pressure indicator in the form of a yellow symbol that lights up on the dashboard instrument panel. It is in the shape of a tyre cross-section which resembles a horseshoe and has an exclamation point.
Tyre pressure monitoring systems have been recently introduce by different automobile manufacturers. Accidents causing mishaps year after year led to the governments take the decision of making TPMS compulsory in vehicles. Europe and the United States were the ones who initially started using TPMS.
The US government passed the Transportation Recall Enhancement, Accountability, and Documentation (TREAD) Act which makes it mandatory for cars to be mounted with tyre pressure monitoring systems for safety concerns.
However, a number of accidents still happen due to tyre related causes but the use of TPMS will ensure tyre- maintenance which will prevent many serious accidents.
The tool is simple yet makes everyday life of drivers, especially the owners of a fleet stress free. You can continously track any loss in tyre pressure even in tubeless tyress which could be life saving.
There are two types of Tyre Pressure Monitoring Systems:
Indirect TPMS
Indirect TPMS is an external system that does not use internal sensors to show that the air pressure inside tyres is less or more. It use speed of tyre rotation while driving and other signals from a vehicle's tyres to find drop in pressure.
First generation iTPMS systems shows that the under-inflated tyres have a slightly smaller diameter than a correctly inflated one. The differences are measured through the sensors attached to the wheel Some of the sensors that is used to take information on tyre pressure are ABS and ESC systems.
Second generation iTPMS detects under-inflation in all four tyres using a particular type of analysis of individual wheels, which is detected using a software.
iTPMS systems were not able to measure or display exact values of the pressure in units. The system had to be reset once the pressures are adjusted and the vehicle had to be driven again.
The reset is normally done either by pressing a button or by adjusting the menu displayed on computer on board. To reset, there is a procedure involved where in the vehicle has to be driven for 20 to 40 minutes.
As iTPMS do not consist of any additional hardware or electronics whatsoever, they are regarded as easy to handle and very customer friendly.
The systems run on external electronics that measure tyre values, iTPMS are much more prone to errors as compared to dTPMS. Even simple things like road surface or wheel alignment can effect the system to produce inaccurate results.
iTPMS are regarded as inaccurate by some, many vehicle manufacturers and customers consider the ease to use iTPMS than the accuracy of dTPMS.
Related Read: A Promise Of Safer Tyres: JK Tyre’s TREEL Tyre Sensors
Direct TPMS
Direct Tyre Pressure Monitoring Systems use pressure sensitive sensors that are fitted onto each wheel (internal wheel rim and not tyre). Since the sensors are physically present inside the tyre, they are able to sense the actual inflation levels and use bluetooth or network connectivity to transfer data to the dashboard or your phone.
Some can also sense temperature changes in the tyres to alert the driver of any heating issues The TPMS products (both OEM and aftermarket) display accurate and real time- tyre pressures whether the vehicle is parked or is on move.
dTPMS are not connected to any electronics on the car. Transmission too is wireless thus forcing the system to depend on battery to sustain the transmission capability.
Some sensors utilize a wireless power system similar to that used in RFID tag reading which solves the problem of limited battery life (electromagnetic induction) Due to this, there is an increase in the frequency of data transmission up to 40 Hz and thus reduces the weight of sensors which can be important in motorsports.
We highly recommend that you avoid stock or aftermarket dTPMS that are installed on the outside of the tyres. These are usually fitted on the valves, are expensive and pretty risky since they are exposed to the elements.
Risk of breakage, theft and damages from fluids are very high. However, even when mounted on the inside, they have their own issues as they are not easily accessible so sorting out any issues will require a lot of work and the RF link must overcome the risk of change in values which effects the tyre ultimately.
The dTPMS sensor consists of the following main functions and requires only few components such as battery, housing, PCB which is a sensor module that is fixed to the valve stem inside the tire:
- Analog/digital converter
- Micro controller
- Oscillator
- system controller
- Transmitters for detecting radio frequency
- Frequency receiver which is usually low.
- pressure sensors
- voltage regulator.
Changing batteries on a dTPMS is not exactly as simple as switching those on your TV remote. Most sensors don't come with replaceable batteries which means that the entire unit will have to be changed.
Since the sensor is internally mounted on the wheel rim, even replacing the unit is tough since changing the TPMS will require the tyre to be dismounted from the wheel and then carefully replaced.
Another task that makes it difficult for dTPMS units to work properly is its need to recognize the sensor positions and ignore the signals from other vehicles.
Some dTPMS units also provide users with numerous advanced monitoring options like remote monitoring options and more. dTPMS are available for all kinds of vehicles, from motorcycles to heavy equipment. They are capable of monitoring up to 64 tires at a single time which makes it usable for commercial vehicles.
Image Credits: Bridgestone
