To determine tread depth, the sensors monitor a tire's rolling characteristics over a longer period of time. The specifics of the tires' altered rolling characteristics are compared with the accumulated empirical data; if the tread is run down to below a tire-specific threshold value, the on-board electrical system signals that a tire change is due.
Conti stresses that drivers also can monitor their treadwear through the tire-wear indicators that Conti molds into its tires. These small ridges between the tread grooves indicate that the recommended minimum allowable tread depth — 3 millimeters in summer tires, 4 mm for winter tires — have been attained.
Regarding vehicle load, software developed by Continental can calculate load by detecting changes in tire rolling characteristics and inform the driver of the respective axle load. Future driver assistance systems will use the load information to adjust their functions to the respective vehicle weight, Conti said.
Continental has been supplying tire pressure sensors since 2002 under its VDO brand, and more recently it has enhanced its offerings in this area with the development of the “Filling Assistant,” a system integrated at the OE level with the vehicle to help the driver fill his or her tires accurately without the use of a tire gauge.
This feature triggers the car's horn when the proper inflation pressure has been achieved. Nissan Motor Co. Ltd. has promoted this feature on several of its models.
Starting this November, TPMS will become mandatory for newly registered passenger cars in the European Union.