Are External Tire Pressure Monitoring Systems Accurate?
2 Answers
Not very accurate. External ones are prone to being lost or flung off. Additionally, since they are exposed externally, they operate in harsh conditions and have significant data inaccuracies. The mechanism of external tire pressure monitoring involves replacing the valve cap with a sensor, which is directly attached to the valve stem. This presses the valve core inward, allowing air from inside the tire to escape, thereby directly detecting tire pressure and temperature. There are five major controversies regarding external tire pressure monitoring systems: 1. Forcibly and permanently pushing the valve core inward, compromising its leak-proof mechanism: The entire tire's internal pressure of over 30 psi relies on the valve core's structure to contain it. The external sensor essentially damages the valve core as a prerequisite, allowing internal tire air to pass through the valve stem and detect pressure and temperature at the valve opening. 2. Centrifugal force generated during driving may cause the valve stem to bend or even tear: Attaching a sensor to the valve stem adds weight. As the tire rotates during driving, the valve stem is subjected to centrifugal force. Prolonged and repeated stress may cause the rubber valve stem to bend or even break. 3. Uncontrollable weight or quality of the valve stem on the wheel rim may lead to air leaks: Since external sensors are directly screwed onto the existing rubber valve stems of the wheel rims, the condition of the original rubber valve stems cannot be controlled. If a leak occurs after installation, it is difficult to determine whether it is due to the aging of the original rubber valve stem. 4. Use of non-military-grade batteries may pose risks when tire temperatures are excessively high: External sensors emphasize the ease of battery replacement, so most use standard button batteries rather than the military-grade batteries specified by manufacturers. When tire temperatures become extremely high, the sensor may malfunction at best, or the battery could pose a danger at worst. 5. Emphasis on easy installation overlooks the need for tire dynamic balancing: Since the focus is on easy installation without removing the tire, dynamic balancing is often skipped after sensor installation. As a result, even if all four tires were initially well-balanced, adding external sensors disrupts their balance, violating proper tire usage and maintenance practices.
As a long-distance driver who frequently hits the road, I've been using an external tire pressure monitoring system for three years and found its accuracy genuinely impressive. The external sensors are simple to install—just screw them onto the valve stems—and the readings typically deviate from actual pressure by only 1-2 psi, which is quite reliable. For instance, when temperatures drop in winter, it immediately alerts me to pressure decreases, allowing me to top up the air without issues. While it might not be as precise as built-in systems, it's more than sufficient for daily use and saves me a lot of hassle. The key is to choose reputable brands and avoid cheap, no-name products that often have significant errors. I opted for imported sensors with software that automatically compensates for temperature effects and provides real-time alerts for pressure discrepancies, ensuring safety. Overall, it has helped me avoid several tire wear risks and even extended tire lifespan. Checking it before long trips gives me much greater peace of mind.
