Do tire pressure monitors work?

One of the key factors to safe motoring is to ensure that the vehicle tires are operated at the recommended tire pressures. There is no substitute to regular checking and maintaining tire pressure especially before embarking on a long journey.

While manual checking and maintaining tire pressure is not a tedious process, some vehicle manufacturers have as standard fitting, a tire pressure monitoring system or TPMS on board the vehicle which alerts the driver of low tire pressure on any of the tires.

Do tire pressure monitors work?

To answer this question, let us take a closer look at the operating systems commonly used and understand how the systems work. Generally, there are two types of TPMS adopted by vehicle manufacturers.rim-fitted-with-pressure-sensor-tire-valve

  1. Direct system-employs a pressure sensor or transmitter attached to each tire rim which sends out a signal to a dashboard signal receiver which interprets to show absolute tire pressure readings for each wheel. This reading alerts the driver to take any necessary action required should the pressure on any wheel be low.
  2. Indirect system-this system uses the vehicle ABS or anti locking braking system wheel speed sensor to pick up changes in rotational speed. When tire pressure changes occur, the circumference of the tire changes and the rotational speed increases. This change in rotational speed is picked up by the illustration-of-indirect-tpmswheel speed sensor and a signal is sent to the dashboard warning light to alert the driver of a possible low tire pressure on any of the wheels. Unlike in the direct system, this system is unable to pinpoint the exact affected tire and the system is also unable to furnish the driver with absolute pressure readings. The driver then has to manually check each tire before taking necessary action.

Now that we understand the principle behind the two systems employed, we are now knowledgeable as to what kind of information the direct and indirect system can provide the driver. Both systems fulfill the purpose of warning the driver of low tire pressure.

While the direct system provides more accurate and specific information on the dashboard panel, it employs more expensive components to relay the information required. The 3 components of the system are tire pressure sensors for each tire, a signal receiver and a dashboard panel indicator. Most aftermarket TPMS fitments are based on this systems.

In the case of the indirect system, the existing ABS or anti-locking braking system wheel speed sensor plays a duel role in picking up rotational speed changes when tire pressure is down. The on board computer will then analyze and alert the driver through a warning light illumination. Since it couples on to existing vehicle systems, it is considered a less expensive system but one that is not readily retrofitted. The downside to such a system is that when all the vehicle tires are low on pressure at the same time, the system may not be able to detect to warn the driver. A manual pressure check and resetting the system would be required for the system to function accurately.

Do tire pressure monitors work? They surely work to warn the driver of possible low tire pressure provided the system requirements are met. In the direct TPMS, the pressure sensors situated inside the wheel rims are sensitive components subject to road shocks continuously and may need replacement occasionally. The indirect system needs regular resetting whenever tires are rotated, changed or when tire pressures are corrected.

In order for a TPMS to work efficiently, regular checking and maintenance of the system is required failing which inaccuracy can be expected.




  1. Hi

    Great Article

    This is decent simple information on tyre pressure that everybody should know.

    It would be very handy to know and get a warning as to when your tyre pressures are low. It is not something I normally check but have had the odd comment here and there that my tyres are looking low.

    To get this information on your dashboard via the In Direct system would be fantastic. Are these pressure monitors expensive?


    • Hello Chris,

      Thank you for dropping by and thank you for your comments.

      Glad you found this article informative and interesting. It is important as far as safety is concerned to ensure that our tires are operating with the correct recommended pressures and having a system to monitor the pressures makes it a lot more convenient.

      The indirect system is usually employed by vehicle manufacturers as a standard fitting as the ABS speed sensor doubles up also as a pressure monitor sensor and therefore retrofitting is a lot more complex.

      As an aftermarket TPMS fitment , the direct system is a lot more easier and straight forward to fit. They are relatively inexpensive and readily available. A good reliable TPMS can be obtained anywhere between $150 and $300 and installation can be done by any reputable tire dealer.

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