the tread is worn down to 4mm (1/16th of an inch). When you see these
“ wear bars ” , the tire is worn out and should be replaced.
Inspect your tires frequently for any of the following conditions and
replace them if one or more of the following conditions exist:
• Fabric showing through the tire rubber
• Bulges in the tread or sidewalls
• Cracks or cuts on the sidewalls
• Cracks in the tread groove
• Impact damage resulting from use
• Separation in the tread
• Separation in the sidewall
• Severe abrasion on the sidewall
If your vehicle has a leak in the exhaust system, a road tire or the spare
tire may be exposed to hot exhaust temperatures requiring the tire to be
replaced.
Safety practices
Driving habits have a great deal to do with your tire mileage and safety.
• Observe posted speed limits
• Avoid fast starts, stops and turns
• Avoid potholes and objects on the road
• Do not run over curbs or hit the tire against a curb when parking
If you vehicle is stuck in snow, mud, sand, etc., do not rapidly spin the
tires; spinning the tires can tear the tire and cause an explosion. A tire
can explode in as little as three to five seconds.
Tire explosions can cause death, personal injury or property
damage. Do not allow anyone to stand near, or directly ahead or
behind the spinning tire.
Never spin the tires in excess of the 55 km/h (35 mph) point
indicated on the speedometer.
Highway hazards
No matter how carefully you drive there ’ s always the possibility that you
may eventually have a flat tire on the highway. Drive slowly to the
2004 Navigator (nav)
Owners Guide (post-2002-fmt)
USA English (fus) Maintenance and Specifications
345
closest safe area out of traffic. This may further damage the flat tire, but
your safety is more important.
If you feel a sudden vibration or ride disturbance while driving or you
suspect your tire or vehicle has been damaged, immediately reduce your
speed. Drive with caution until you can safely pull off the road. Stop and
inspect the tire for damage. If the tire is under-inflated or damaged,
deflate it, remove wheel and replace it with your spare tire and wheel. If
you cannot detect a cause, have the vehicle towed to the nearest repair
facility or tire dealer to have the vehicle inspected.
Tire pressure monitoring system (TPMS)(if equipped)
When the tire pressure monitoring
system warning light is lit, one or
more of your tires is significantly
under-inflated. you should stop and
check your tires as soon as possible,
and inflate them to the proper pressure as indicated in the vehicle ’ s tire
information placard. Driving on a significantly under-inflated tire causes
the tire to overheat and can lead to tire failure. Under-inflation also
reduces fuel efficiency and tire tread life, and may affect the vehicle ’ s
handling and stopping ability. Each tire should be checked monthly, the
spare tire every six months. Tire pressure should be set when cold to the
recommended inflation pressure as specified in the vehicle placard and
owner ’ s manual.
Note: This vehicle is equipped with a Tire Pressure Monitoring System
(TPMS) which 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 14 to 28 kPa (2 to 4 psi)
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 20.7 kPa (3 psi) for a drop of 16.6 ° C (30 ° F) in
ambient temperature. This lower pressure value may be detected by the
TPMS as being significantly lower than the cold placard pressure, and
activate the TPMS warning for low tire pressure. If the low warning light
2004 Navigator (nav)
Owners Guide (post-2002-fmt)
USA English (fus)Maintenance and Specifications
346