November 2014 the use of tire pressure monitoring systems RDKS/TMPS is mandatory.
What to consider for new car buyers?
Who buys a new passenger car or a new motor home (class M1) with the first registration from 01.11.2014, will have integrated in his vehicle from the manufacturer a tire pressure monitoring system (RDKS/TPMS) according to ECE-R 64. There are basically two different systems that are used ex works: the
Direct measuring system (with tire pressure sensor in the wheel) or the Indirect measuring system (via in-vehicle ABS sensors).
What is the difference between direct measuring and indirect measuring systems??
Direct measuring tire pressure monitoring system
Here each wheel has its own air pressure sensor, the information is sent by radio to the control unit and is then shown on the vehicle display. The direct measuring system has thereby several Advantages:
– exact measurement of all values like air pressure, temperature, wheel position
– Alarm already from 0.2 bar pressure difference or pressure drop is possible
– Spare wheel is monitored with
– Air pressure monitoring also takes place while the vehicle is stationary
Disadvantages:
– the system is more complex and expensive
– the sensors can be damaged during tire mounting
– Lifetime of the batteries in the tire pressure sensors is limited (4-10 years) and can not be changed
– additional purchase costs (on average currently approx. 75,- € per RDKS sensor) for each summer, winter and spare wheel
– clear additional expenditure with maintenance and tire change
There are different types of sensors. For one thing
Original sensors, these are already pre-programmed with the vehicle-specific details, so the sensor can only be used in some specific vehicles. Alternatively, there are a number of manufacturers of Universal sensors, these are not pre-programmed and can be easily integrated into most vehicles. The main manufacturers include ALLIGATOR sens.It, Cub Uni-Sensor, SCHRADER with the EZ-Sensor, the company Huf (IntelliSens) and Conti VDO with the REDI sensor, which is on the market as a multisensor for various vehicle brands.
Indirectly measuring tire pressure monitoring system
As a tire with pressure loss reduces its rolling circumference and rotates faster, this is measured by the existing ABS sensors and detected by the control unit. This evaluates the signals of the wheel speed sensors and compares them with each other. If the difference cannot be attributed to the driving situation, an appropriate warning lamp lights up in the instrument cluster.
– cheap solution, only a changed software and a control are necessary, in combination with a runflat tire optimal solution
– no additional purchase costs for tire pressure sensors
disadvantages:
– inaccurate z.B. No indication of the exact pressure loss and temperature measurement
– creeping air loss on both wheels of an axle is not detected, only differences>0.5 bar can be detected
– no measurement of tire pressure when the vehicle is stationary
Which characteristics must the RDKS/TMPS system meet??
The EU law prescribes the following features:
– Warning in case of pressure loss of a single tire (within 10 minutes): 20% lower than operating pressure (Pwarm) at 1.5 bar
– warning in case of pressure loss of all four tires (sudden and gradual loss): 20% lower than operating pressure (Pwarm) at 1.5 bar
– Detection of pressure loss at speeds from 40 km/h up to the maximum mileage of the car
– Data transmission at 434 MHz
Up to now, only the direct-measurement systems with tire pressure sensor in the wheel have been able to fulfill this requirement. These can also measure the exact wheel position, the temperature in the wheel and the exact air pressure (even when stationary) and send them by radio to the on-board network. The driver can then read this information on the vehicle display and react directly in the event of pressure loss.
During the main inspection, a non-functional tire pressure control system is considered to be a "defect" according to §29 StVZO minor defect (no Tüv) and must be repaired immediately by the vehicle owner. This also means that, for vehicles with a direct measuring system no wheels without RDKS/TMPS sensor may be installed, since thus the operating license of the vehicle expires, since then a Nichtvorschriftsmäßigkeit of the vehicle is present.
What do vehicle owners need to be aware of when changing a wheel and what should they pay attention to??
Since the complex technology of tire pressure monitoring systems makes it difficult for the owner to change the wheel himself, the tire service at the dealer and RDKS expert takes on greater importance. A significant amount of additional time spent installing, maintaining and programming sensors and learning or. Initialization of the tire pressure monitoring system after installation, cause additional costs. This leads to a significant increase in service prices for tire servicing on vehicles with TPMS, mainly due to the increased maintenance effort and the additional work steps required for tire changes. For the timely supply of suitable winter complete wheels with RDKS/TMPS sensors, we recommend all new car buyers to deal with the topic now already. Currently, suitable winter wheels with TPMS sensors can already be ordered here for many vehicle models which have the standard tire pressure monitoring system.