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21/03/2018
Tire Pressure Monitoring Systems and vehicle-type approval

TPMS 

A number of articles on previous Pneurama issues already developed the theme “Tires and pressures" (n°4-5/2014 and n°1/2015) illustrating how a TPMS - Tire Pressure Monitoring System works; here we deal with the most crucial aspects of the current legislation.

 

Donaldo Labò

Throughout the European Union, the mandatory use of tire pressure monitoring systems on passenger cars (M1) – on new approvals since November 2012, and on all new registrations since November 2014 - has been ratified by Regulation (EC) 661/2009 "concerning type-approval requirements for the general safety of motor vehicles, their trailers and systems, components and separate technical units". This Regulation, which brings under one umbrella the many rules scattered in numerous Directives, simplifies and strengthens the rules on vehicle type-approval to ensure greater safety and environmental protection. It involves the use of low rolling resistance tires, tire pressure monitoring systems, as well as stability control systems, lane departure warnings, emergency braking devices, etc.

As a general requirement, vehicle manufacturers (and components) are called upon to demonstrate that all new vehicles sold and registered are "approved" in strict compliance with the regulation, whose provisions are in line with those set out in the Directive 2007/46 /EC on vehicle type-approval.

TPMS sensors installed as standard equipment on a vehicle (whether direct or indirect), must be subjected to operating checks prior to approval which include, among other things, operating tests starting at 40 km/h up to the maximum vehicle speed, detection of pressure loss following an accidental event (puncture test), actuation of the warning signal following a 20% pressure loss in at least one tire, signal malfunctions, etc.

As already observed, tire pressure monitoring systems have therefore become a mandatory requirement for passenger transport vehicles <3.5 t. As a result, deactivation or modification of the system is not permitted: the vehicle would no longer be in compliance with current traffic laws, and therefore subject to law suits (civil, criminal etc.) in case of accidents, with damage to people and properties.

In the vehicle’s user manual all related warnings are illustrated, i.e. reset and initializing procedures following routine mounting/demounting operations on one or more tires, when front and rear wheels are rotated, and/or simple correction/variation of the tire pressure following routine checks.

After a reset, in fact, the main parameters of the tire – pressure, rolling radius with "indirect" systems - are memorized and set by the system as the reference values and any changes are immediately signalled to the driver. This results in an obvious need to control tire pressure with precise and reliable pressure gauges.

From the above, operations such as regular checks when a vehicle enters a workshop, are clearly essential: "check-in" or "test-before-touch", visually checking the status of the valves, checking alarm signals, sensors (direct systems), followed by diagnostic and programming tools where necessary, to ensure that the vehicle, upon exiting the workshop after working on the tire/wheel unit and/or any other element of the system, maintains the correct mode of operation of the TPMS as prescribed by the legislation in force.

The need for correct equipment, proper timing and professionalism entails unavoidable costs, but the only acceptable result is to guarantee the safety of modern vehicles.

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