User Manual - Page 191

For 2019 Grand Cherokee.

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The tire pressure will vary with temperature by approxi-
mately 1 psi (7 kPa) for every 12°F (6.5°C). 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. The tire pressure will also increase as the
vehicle is driven. This is normal and there should be no
adjustment for this increased pressure.
Refer to “Tires” in “Servicing And Maintenance” for infor-
mation on how to properly inflate the vehicle’s tires.
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 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 Pres-
sure 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
(24 km/h) in order for the TPMS to receive this informa-
tion.
For example, your vehicle may have a recommended cold
(parked for more than three hours) placard pressure of 33
psi (227 kPa). If the ambient temperature is 68°F (20°C) and
the measured tire pressure is 28 psi (193 kPa), a tempera-
ture drop to 20°F (-7°C) will decrease the tire pressure to
approximately 24 psi (165 kPa). This tire pressure is low
enough to turn ON the “Tire Pressure Monitoring Telltale
Light.” Driving the vehicle may cause the tire pressure to
rise to approximately 28 psi (193 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.
5
SAFETY 189
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