Dodge 2009 Challenger Owner's Manual page 310

308 STARTING AND OPERATING
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 warn-
ing (Tire Pressure Monitoring [TPM] Telltale Light) illu-
minates, you must increase the tire pressure to the
recommended cold placard pressure in order for the
"TPM Telltale Light" to turn off. The system will auto-
matically update and the "TPM 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 68°F
(20°C) and the measured tire pressure is 27 psi (186 kPa),
a temperature drop to 20°F (-7°C) will decrease the tire
pressure to approximately 23 psi (158 kPa). This tire
pressure is sufficiently low enough to turn ON the "TPM
Telltale Light." Driving the vehicle may cause the tire
pressure to rise to approximately 27 psi (186 kPa), but the
"TPM Telltale Light" will still be ON. In this situation, the
"TPM Telltale Light" will turn OFF only after the tires are
inflated to the vehicle's recommended cold placard pres-
sure value.