How tyre pressure monitoring systems work
Tyre pressure monitoring systems (TPMS) are becoming quite common as standard equipment on many cars or could be fitted as an aftermarket accessory system.
Some TPMS will only warn of tyre pressure drop at a particular wheel/s while others can also show the individual tyre pressures.
TPMS operate in two main ways – by indirect and direct measurement.
The former is typically original equipment and uses signals generated by the ABS brake system wheel speed sensors to allow the system to ‘deduce’ a pressure difference.
A change in pressure on a wheel will change its effective diameter and thus its rotational speed relative to the other wheels, leading to the system alerting the driver.
As the speed sensor is separate from the wheel and tyre, no recalibration to advise the system of the new wheel positions will be required after a tyre rotation.
Direct systems have pressure sensors mounted on the wheel (either internally or externally) that measure the actual pressure in each tyre and transmit information back to the system monitor.
Externally mounted sensors (common in the aftermarket) are generally screwed onto the valve stem and can be easily removed and refitted at the same ‘corner’ of the car after tyre rotation is complete.
Where internal sensors are fitted, the new wheel location after a tyre rotation will need to be programmed in.
It’s usually relatively easy to do through the onboard system menu.
In a small number of cases the vehicle dealer may have to re-program the system and costs may apply.
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The information in this article has been prepared for general information purposes only and is not intended as legal advice or specific advice to any particular person. Any advice contained in the document is general advice, not intended as legal advice or professional advice and does not take into account any person’s particular circumstances. Before acting on anything based on this advice you should consider its appropriateness to you, having regard to your objectives and needs.