When inflating your tires
When putting air into your tires (such as at a gas station or in your
garage), the Tire Pressure Monitoring System may not respond
immediately to the air added to your tires. Here are the details:
•
The tire pressure monitor sensors mounted in your wheels updates
your vehicle with tire pressure information only once every minute,
therefore it may take up to a minute for the light to turn off after you
have filled your tires to the recommended tire pressure.
•
If your vehicle has been parked for over 15 minutes, the sensors go
into a low power mode to conserve battery life and therefore only
transmit about once an hour. If you inflate your tires under these
conditions, the light could take up to an hour to turn off after you
have filled your tires to the recommended tire pressure.
For these reasons, the low tire warning light is NOT a substitute for
using an accurate tire gauge when checking and filling your tires. The
best way to turn off the low tire warning light is to fill your tires to the
recommended tire pressure and drive your vehicle — the tire pressure
sensors in your wheels will update your vehicle with the updated tire
pressure when your vehicle reaches a speed of 20 mph (32 km/h) for at
least a minute.
How temperature affects your tire pressure
The Tire Pressure Monitoring System (TPMS) monitors tire pressure in
each pneumatic tire. The pressure in each tire is dependent upon several
factors, one of them being the contained air temperature (temperature of
the air inside the tire). As the contained air temperature increases, the
tire pressure also increases. While driving in a normal manner, a typical
passenger tire inflation pressure may increase approximately 2 to 4 psi
(14 to 28 kPa) from a cold start situation. This increase in tire pressure
is due to an increase in the contained air temperature. Contained air
temperature is dependent upon several factors such as rate of tire
rotation, tire deflection, amount of braking, etc. In similar manner, the
tire pressure will decrease if the contained air temperature decreases.
For example, if the vehicle is stationary over night with the outside
temperature significantly lower than the daytime temperature, the tire
pressure may decrease approximately 3 psi (20.7 kPa) for a drop of 30°
F (16.6° C) in ambient temperature. This lower pressure value may be
detected by the TPMS as being significantly lower than the cold pressure
indicated on your vehicles Safety Compliance Certification Label, and
activate the TPMS warning for low tire pressure. If the low warning light
is on, visually check each tire to verify that no tire is flat. If one or more
2006 Navigator
(nav)
Owners Guide (post-2002-fmt)
USA
(fus)
Tires, Wheels and Loading
254
