Tire Pressure Monitoring System
As part of the effort to increase awareness of the need to maintain proper tire pressure, the U.S. government has taken steps to make it easier for drivers to be aware of potentially unsafe low pressure in their tires. As of the 2008 model year, the National Highway Traffic Safety Administration (NHTSA) now requires that all passenger cars and light trucks feature the Tire Pressure Monitoring System (TPMS). In conjunction with the new requirements, the Alliance of Automobile Manufacturers (AAM) has initiated a consumer safety campaign focusing on the importance of maintaining proper tire pressure.
TPMS is an automated system that monitors the air pressure in a vehicle tires. When air pressure in one on more tires drops to 25% or less the correct pressure, a warning indicator will alert the driver. TPMS typically delivers these alerts to the driver through one or two types of warning lights on the dashboard.
1. The first alert uses the official TPMS symbol, which is a cross-section of a tire with an exclamation mark in the center.
2. The second is a top-view graphic image of a car that indicates which tire or tires is low.
How TPMS Works
Tire pressure is monitored through one or two methods: direct or indirect. Direct TPMS monitors the actual air pressure inside each tire via a sensor mounted within the tire. Indirect TPMS measures tire pressure by monitoring the speed and rotation of each individual wheel. When a significant variation in speed and rotation is detected in one or more wheels when compared with others, it is often an indication of under-inflation. This information is then transmitted to the vehicle’s on-board computer and the driver is alerted.
While TPMS systems offer increased safety to drivers through low pressure warnings, they are not meant to be a substitute for proper tire pressure maintenance. Both the NHTSA and the AAM urge drivers to check their tire pressure at least once a month and always prior to a long trip. Be sure to read our article on the importance of correct air pressure as well for even more in-depth information.
