What Does Indirect Tire Pressure Monitoring Mean?
2 Answers
Indirect (Wheel-Speed-Based-TPMS, abbreviated as WSB), this system uses the wheel speed sensors of the car's ABS system to compare the rotational speed differences between tires, thereby achieving the purpose of monitoring tire pressure. The specific details are as follows: 1. ABS Working Principle: ABS determines whether a wheel is locked by using wheel speed sensors, thereby deciding whether to activate the anti-lock braking system. When tire pressure decreases, the vehicle's weight causes the tire diameter to shrink, leading to changes in vehicle speed. These changes can then be used to trigger an alarm system to warn the driver. This method is cost-effective but cannot directly measure specific values, making it less intuitive. 2. Indirect Tire Pressure Monitoring Working Principle: The cost of indirect tire pressure monitoring devices is much lower than direct ones. It essentially uses the speed sensors on the car's ABS braking system to compare the rotation counts of the four tires. If one tire has lower pressure, its rotation count will differ from the others. By utilizing the same sensors and sensing signals as the ABS system, with just a software adjustment in the car's computer, a new function can be established in the driving computer to warn the driver that one tire has lower pressure compared to the other three.
Indirect tire pressure monitoring works through the wheel speed sensors in the ABS system, eliminating the need for separate sensors inside the tires. This system calculates the rotational speed differences between the four wheels to infer tire pressure. If any tire is leaking, its rotation speed will differ, triggering a system alert to prompt a check. Compared to direct monitoring, it saves on sensor costs but is less precise. Sometimes, after inflating the tires, you have to manually reset the system. Last year, I drove a friend's car equipped with this feature and experienced it firsthand—it alarmed at the slightest drop in tire pressure, making me go to a repair shop for a check.
