TPMS means tyre pressure monitoring system. It works through small electric sensors attached to each tyre’s air valve for monitoring the air pressure. There is another type of TPMS sensor that works by monitoring your car’s ABS system. The data is fed back to the car’s control panel and displayed on the digital dashboard cluster. While older implementations relied on the TPMS light which would blink yellow when there was a change in air pressure of one or more tyres, newer systems allow realtime psi monitoring of air pressure in each tyre through a digital infographic interface.
The TPMS functionality is not part of standard equipment and is typically offered in higher end variants. Here are certain benefits offered by the TPMS functionality that may help you in making a purchase decision.
Provides visual cues about low air pressure in one or more of your tyres.
Reduces the risk of tyre failures due to low air pressure.
Helps improve fuel economy by ensuring optimal tyre pressure.
Decreases the chances of uneven or premature tyre wear usually caused by improper inflation.
Helps improve your car’s traction and handling.
There are two types of TPMS sensors used by car makers - direct and indirect.
Direct TPMS sensors are basically pressure monitoring modules which are attached to the air valve and are powered by a small battery. The sensors send a remote signal to the car’s system when they detect a drop in the air pressure (usually 25% or more).
Indirect TPMS is a software-based system that uses the vehicle's Anti-lock Braking System (ABS) wheel speed sensors to monitor tyre pressure. It doesn't have pressure sensors inside the wheels. The core principle is that a tyre with lower pressure has a smaller rolling radius than a properly inflated tyre. This difference in rolling radius causes the wheel to rotate at a slightly faster speed to cover the same distance as the other wheels. The ABS system, which constantly monitors the rotational speed of each wheel, detects these subtle differences and allows the car to detect a loss of air pressure in one or more of the tyres.
Here’s a table to help you understand the advantages and disadvantages of both types of tyre pressure monitoring systems.
TPMS |
Advantages |
Disadvantages |
|---|---|---|
Direct TPMS |
More accurate |
Expensive, may drive car’s cost up |
Provides actual psi reading |
Easier to damage as the sensor sits inside the tyre itself |
|
No reset needed after tyre change |
- | |
Wireless, battery operated |
- | |
Indirect TPMS |
Cheaper to implement |
Requires recalibration after tyre change |
Needs less calibration and maintenance |
May provide inaccurate information if tyres are of different size |
|
| - | Does not provide actual air pressure readings |
Ultimately, regardless of their specific pros and cons, both types of TPMS enhance vehicle safety.
When you start your car, all lights on the dashboard light up, look for the TPMS light to know if your car has the tyre pressure monitoring system or not. Check the image below to identify the TPMS sensor light.
Q1: How far can I drive with the TPMS light on?
As little as possible. A TPMS light indicates that one or more of your tyres have a pressure issue and you should stop immediately to check the same. Driving on under-inflated tyres can lead to reduced fuel efficiency, uneven and accelerated tyre wear, and poor handling and braking performance.
Q2: Will the TPMS light come on if tyres are over-inflated?
Most TPMS systems are designed to primarily alert to under-inflation. While some more sophisticated systems may have a high-pressure threshold, it's less common. The light may come on if you significantly over-inflate your tyres.
Q3: How to replace a faulty TPMS sensor battery?
The batteries in most TPMS sensors are not designed to be replaced separately. The entire sensor is typically a sealed unit, so a sensor replacement is usually necessary. But you don’t have to worry about frequent replacement as TPMS sensor batteries usually last up to 10 years.
Q4: Can TPMS be added as an aftermarket accessory?
Yes, you can add an aftermarket TPMS system to vehicles that didn't originally come equipped with one. Internal Sensors replace your existing valve stems, similar to the factory TPMS. They require professional installation (tyre removal, mounting, balancing, programming). On the other hand, external Sensors also known as Valve Cap Sensor screw onto your existing valve stems. They are much easier to install, but they can be more prone to theft or damage, and may affect wheel balance slightly.
So, there you have it – a comprehensive look at TPMS, from its basic definition to the nuances of direct versus indirect systems, and answers to some common questions. Whether your car has the system built-in or you're considering an aftermarket addition, understanding TPMS is vital for responsible car ownership.
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