What is TPMS?Ā
Direct TPMS is a warning system that warns a vehicle's operator of an unsafe change in the air pressure in one or more of the tires. Readings are provided by pressure sensing transmitters mounted inside each tire and sent to a central computer (ECU) for display on the dashboard. A warning indicator light on the instrument panel and an audible warning notify the driver if a 25% drop in pressure occurs.
How do I know if my vehicle is equipped with TPMS?Ā
In the U.S., if you purchased a car or light duty vehicle under 10,000 lbs, manufactured after September 1, 2007, you have TPMS. If your model was manufactured after October 5, 2005, youĀ mayĀ have TPMS. Also, prior to the legislation, some higher-end vehicles also came equipped with TPMS as a premium option. Among other matters, within TREAD Act of 2000, the U.S. federal government mandated the required implementation of TPMS on all new vehicles in the following phased rollout:
- 20% of new vehicles from Oct 5, 2005-Aug 31, 2006
- 70% of new vehicles from Sept 1, 2006-Aug 31, 2007
- 100% of new vehicles from Sept 1, 2007 and beyond
How does tire pressure affect my safety?Ā
As most drivers check their tires only at service intervals and when problems occur, motorists can benefit greatly from a greater awareness of tire pressure and its effects on safety while driving. The National Highway Traffic Safety Administration (NHTSA) has estimated that 660 U.S. automobile accident fatalities annually are caused by underinflated tires. Dry and wet surface handling suffers with underinflated tires, including:
- Skidding and loss of control of the vehicle in a pronounced curve, such as an off-ramp from the highway, or when taking any curve at a high speed
- Hydroplaning on a wet surface, which can affect both stopping distance and skidding or loss of control
- Crashes from flat tires or blowouts
What exactly does it mean when my TPMS warning light comes on?Ā
If the TPMS warning light comes ON and flashes ON for one second and OFF for three seconds, this indicates a malfunction with the vehicle's TPMS system.
If the TPMS warning light comes ON and stays ON, take caution. This means that one or more of your tires may have a low-pressure condition. You should carefully slow the vehicle and park in a safe and secure place. You should then inspect all of your tires and check the air pressure. The correct air pressure for your vehicle can be found on the placard, usually located on the inside door panel.
Why does tire pressure change?Ā
Many factors affect tire pressure including ambient temperature changes and tire damage such as punctures. Tire pressure drops about 1 psi for every 10°F drop in ambient temperature. Additionally, tires can lose as much as 1.5 psi per month as air escapes the tire and rim naturally.
What should my tires be inflated to and where can I find that?Ā
Tires should be inflated to the vehicle manufacturer's recommendation as found on the vehicle tire information door placard. The vehicle placard is normally located on the inside door panel or door itself. In many cases the specified tire pressure can also be found in the vehicle owner's manual. The pressure indicated on the sidewall of the tire should not be your guide, as that is the maximum inflation pressure for the tire itself, not for the tire when used on your specific vehicle.