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How Tyre Pressure Monitors Work

How Tyre Pressure Monitors Work: A Quick Look at TPMS

The premise of measuring the atmospheric pressure inside the tyre is how our tyre pressure monitors work. Air pressure inside a tyre enables the entire wheel system to function smoothly. The air inside provides a cushion between the rim and the tyre, easing rolling resistance and lessening road friction, ensuring a comfortable and safe ride. The standard units of measurement for tyre pressure are psi (or pounds-per-square-inch) and kPa (or kilopascals). 

sample tyre pressure guide

Why do you need tyre pressure monitors?

The reasons mentioned above are why you must always get an accurate measure of your car’s tyre pressure. 

A low tyre pressure means the vehicle is under-inflated and will cause the tyre to lose grip and handling on the road. Conversely, a higher tyre pressure causes the centre of the tyre to harden, making it harder to steer. Both situations cause premature tread wear, increased consumption of petrol, and unsafe vehicle conditions for driving. 

It is important to note that external factors can also affect the tyre pressure and cause significant changes such as temperature, road conditions and weight load. 

Knowing how tyre pressure monitors work and using a reliable one is a must! And if used correctly, it can give an accurate reading on car tyre pressure.

Different tyre pressure monitors out there

An old-generation tyre pressure gauge requires you to look at the needle on the device (for analog/standard gauges) or the reading on the display screen (for digital gauges) to get a tyre pressure reading. You can also use the local petrol station’s air compressor gauge to get your manual tyre pressure readings  (which can be inaccurate at times, though).

How tyre pressure works
analog tyre pressure gauge

How tyre pressure works
digital tyre pressure gauge

However, using these devices can be cumbersome and time-consuming since you need to do this outside of the vehicle and operate the device to perform the actual check. Just imagine that you’re on a long highway on a road trip down south. There’ll be no way of monitoring your current tyre pressure unless you stop. 

The newer alternative is installing a tyre pressure monitoring system (TPMS). It measures tyre pressure via sensors installed inside the tyre or valves. These sensors transmit data to an onboard computer system (If OEM version) to process and display on a separate screen or the dashboard display or your phone if aftermarket TPMS is used.

What cars have factory-made TPMS?

Newer vehicles models today come pre-installed with their OEM tyre pressure monitoring systems. They may have varying TPMS units installed on them, but all serve the same function: warn drivers in real-time if tyre pressure reaches a critically low level and severe under-inflation (around 20% to 25%) occurs on their tyres.  

The European car market was the first to offer tyre pressure monitors on vehicles when it became an optional feature on luxury brands of the 1980s. The USA, meanwhile, paved the way for TPMS’ proliferation when the US Congress passed the TREAD Act of 2000. This landmark legislation mandated American manufacturers to install tyre pressure monitoring systems on all vehicles under 4.5 tonnes to alert car owners of the under-inflation of their tyres. 

An American-imported car, SUV, or truck manufactured from 2008 or later will be sure to have an OEM or factory-made TPMS. The European Union (including the United Kingdom) followed suit with their regulations. Now, they have been exporting TPMS-fitted cars since 2012. 

The global market also expects Russia and the big Asian countries in car production (Japan, South Korea, Taiwan, India, and China) to achieve 100% TPMS compliance on their exports in the next couple of years. This is given that their respective governments have already passed their legislation regarding tyre pressure monitoring systems. 

What aftermarket TPMS options are there?

The government has yet to mandate local car manufacturers to install a TPMS on their vehicles in Australia. But don’t worry if you want to have one yourself. The market is plush with aftermarket TPMS options for you to choose from. The choice now boils down to:

Direct TPMS or Indirect TPMS?

The fundamental difference between the two is how they answer, “how different tyre pressure monitors work?”. 

Direct TPMS uses sensors mounted inside each tyre or attached to the tyre valve to measure tyre pressure. And now, most TPMS even measure tyre temperature. These sensors transmit real-time data to a central onboard computer, display or your phone that displays the processed information. 

TODAY, most OEM and aftermarket TPMS are of this model since it gives more accurate tyre pressure readings. It also synchronises faster if you ever replace or re-inflate your tyres. Although on the more expensive side of the two, many consider this method the chosen one. 

Indirect TPMS, on the other hand, works with the data from the wheel speed sensor of a car’s Anti-lock Braking System to determine if a tyre is under-inflated or not. This tyre pressure monitoring system works on the premise that if tyre pressure is lower than the prescribed level, the rate of wheel revolution is faster since the “smaller tyre” tries to compensate with the other tyres’ revolution by rotating faster. 

This variety of TPMS is more affordable and requires lesser maintenance than more oversized its direct counterpart. However, how tyre pressure monitors work like this is sometimes inaccurate, especially if you’ve switched to a smaller or bigger tyre. You also need to reset the system if you re-inflated or routine tyre rotation. 

direct TPMS vs indirect TPMS

Features of the TPMS you need to consider

1. Pressure Range

Sedans and SUVs built for city driving usually need 25 to 40 psi on the 4WDs. However, it functions below 20 psi to traverse beach drives, while trucks and caravans use 50 psi to accommodate more oversized loads. Also, the number of sensors depends on the number of tyres needed by the vehicle to operate. 

But also consider the spare tyres, as, over time, they lose tyre pressure and need re-inflation regularly. They should fit the vehicle you plan to install it in, as its pressure range and number of sensors.

2. Durability and Quality

Australia exposes vehicles in the harshest of environments – whether it is in the heat, rain, snow, sand, mud, etc. How tyre pressure monitors work consistently depends on how they can cope with the elements. Consider a TPMS made from quality and technologically advanced materials that can withstand any weather condition and the Australian weather conditions. 

3. Ease of Use

A quick read of the manual should allow you to install the sensors easily, mount the display, and operate the system. Avoiding complications, whether you fit the device on a motorcycle, car, SUV, 4WD, caravan, or truck, is a must when dealing with driver’s safety.

4. Budget

A TPMS can range from less than $100 to over $1,000. And the price depends on the vehicle to be fitted and the features included in the system. But as we’ve said, consider this purchase as an investment – an investment to car safety, better fuel economy, longer tyre life, and more comfortable drives. 


For the best aftermarket TPMS, you need not only consider the features. You should also note where the unit comes from. TyreWatcher is a direct-to-consumer/business company that provides quality and innovative tyre pressure monitoring systems for all types of vehicles. It is a true-blue Australian enterprise founded for and with the Aussie consumer and the Australian environment. If you’re looking for the latest in Tyre Accessories and TPMS units at affordable prices and backed by credible live customer support, don’t pass up the opportunity to get in touch with us today.

How to troubleshoot factory tyre pressure sensors?

How tyre pressure monitors work correctly depends on their sensors. And manufacturers make reasonably reliable OEM or factory-made tyre sensors for their TPMS. However, like most other electronic devices, they run into trouble once in a while.

OBD2 Australia TPMS sensors

One common concern regarding these sensors (of direct TPMS) is the difficulty in dismounting them. Since most carmakers initially installed the sensors inside a tyre rim, you will need to remove the tyre entirely to get to the device. That is why most of these sensors have long-lasting batteries to limit the inconvenience brought about by this event. 

Also, since factory tyre pressure sensors are part of a proprietary system, you may need expert help in mounting/dismounting and servicing them. Most tyre shops offer this as a service, and OBD2 Australia sell the aftermarket sensors that can replace the OEM ones and the tools needed to reset these tyre sensors.

Corrosion is another enemy of these sensors, particularly those installed externally or in the tyre valve. At worst, you need a complete replacement of these sensors. 

Finally, factory tyre pressure sensors can pick up signals from other vehicles and vice versa. This situation may create inaccuracies in the data gathered. Sensor position is crucial in this situation to transmit unobstructed data to the car’s computer. Some concerns also arise regarding how easy it is to track vehicles using these sensors. But encrypting radios signals to and from the sensor is enough to protect your privacy.

Are there other issues on how tyre pressure monitors work?

TPMS also suffer other issues aside from their sensors. Since the system functions on electronics, if any part is defective, the whole system breaks down. A non-functioning display screen means no tyre pressure information is given to drivers. 

Transmitters and receivers also get mixed signals or fail to send data altogether due to incorrect positioning and low frequency. So ensure you have a robust system and will have interference protection.

Our Final Word

However, the biggest issue of drivers with how tyre pressure monitors work is relying on them too much. Sometimes they forget that these devices are still prone to malfunction or defects caused by outside factors.

A TPMS should only act as a supplemental tool to basic car safety. Vigilance and awareness on the road and regular checking and maintenance of your vehicle are paramount to deter mishaps. Nevertheless, if you are to get one for your car, motorcycle, truck, SUV, or 4WD, make sure you get one that knows the technology and Australian conditions very well

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