How Does the Tire Pressure Monitoring System Work in Cars?

[PeterLee]

There are two principles behind tire pressure monitoring in cars. Below are the detailed introductions and comparisons of these two principles: 1. Direct Tire Pressure Monitoring. Direct tire pressure monitoring devices use pressure sensors installed in each tire to directly measure the tire's air pressure. The pressure information is then transmitted wirelessly from inside the tire to a central receiver module, which displays the pressure data for each tire. The system automatically alerts the driver when the tire pressure is too low or if there is a leak. 2. Indirect Tire Pressure Monitoring. The working principle of indirect tire pressure monitoring is: when the pressure in a tire decreases, the vehicle's weight causes the rolling radius of that wheel to become smaller, resulting in a faster rotation speed compared to the other wheels. By comparing the differences in rotation speeds among the tires, the system monitors the tire pressure. Indirect tire pressure alert systems essentially rely on calculating the rolling radius of the tires to monitor pressure. 3. Characteristics of Both Types of Tire Pressure Monitoring. Both types of tire pressure monitoring devices have their pros and cons. Direct tire pressure monitoring devices offer more advanced features, allowing real-time measurement of the actual instantaneous pressure inside each tire and easy identification of the faulty tire. Indirect systems are relatively cheaper to manufacture, and cars already equipped with 4-wheel ABS (each tire equipped with one wheel speed sensor) only require a software upgrade. However, indirect tire pressure monitoring devices are not as accurate as direct systems and cannot pinpoint the faulty tire. Additionally, system calibration is extremely complex, and in some cases, the system may fail to function properly, such as when both tires on the same axle have low pressure.