The Tire Pressure Monitor System (TPMS) will warn the driver of a low tire pressure based on the vehicle recommended cold placard pressure.
The tire pressure will vary with temperature by about 1 psi (7 kPa) for every 12ºF (6.5ºC). This means that when the outside temperature decreases, the tire pressure will decrease. Tire pressure should always be set based on cold inflation tire pressure. This is defined as the tire pressure after the vehicle has not been driven for at least three hours, or driven less than 1 mile (1.6 km) after a three hour period. The cold tire inflation pressure must not exceed the maximum inflation pressure molded into the tire sidewall. Refer to "Tires - General Information" in "Starting and Operating" for information on how to properly inflate the vehicle's tires. The tire pressure will also increase as the vehicle is driven - this is normal and there should be no adjustment for this increased pressure.
The TPMS will warn the driver of a low tire pressure if the tire pressure falls below the low-pressure warning limit for any reason, including low temperature effects and natural pressure loss through the tire.
The TPMS will continue to warn the driver of low tire pressure as long as the condition exists, and will not turn off until the tire pressure is at or above the recommended cold placard pressure. Once the low tire pressure warning (Tire Pressure Monitoring [TPM] Telltale Light) illuminates, you must increase the tire pressure to the recommended cold placard pressure in order for the "Tire Pressure Monitoring Telltale Light" to turn off. The system will automatically update and the "Tire Pressure Monitoring Telltale Light" will turn off once the system receives the updated tire pressures. The vehicle may need to be driven for up to 20 minutes above 15 mph (25 km/h) in order for the TPMS to receive this information.
For example, your vehicle may have a recommended cold (parked for more than three hours) placard pressure of 30 psi (207 kPa). If the ambient temperature is 68ºF (20ºC) and the measured tire pressure is 27 psi (186 kPa), a temperature drop to 20ºF (-7ºC) will decrease the tire pressure to approximately 23 psi (158 kPa). This tire pressure is sufficiently low enough to turn ON the "Tire Pressure Monitoring Telltale Light." Driving the vehicle may cause the tire pressure to rise to approximately 27 psi (186 kPa), but the "Tire Pressure Monitoring Telltale Light" will still be ON. In this situation, the "Tire Pressure Monitoring Telltale Light" will turn OFF only after the tires are inflated to the vehicle's recommended cold placard pressure value.
CAUTION!
NOTE:
Under-inflation also reduces fuel efficiency and tire tread life, and may affect the vehicle's handling and stopping ability.