Jaguar XK JJM 18 02 30 701 - Manual (Page 225)

259
Wheels and Tires
R
Ambient temperature pressure
compensation
If the intended journey will take the vehicle
into an area where the ambient local
temperature is known to be lower than the
journey start point, tire pressure under
inflation could occur.
A colder ambient local temperature will
reduce pressure within the tire. An effect
is to decrease sidewall height and to
increase tire shoulder wear with the
potential for tire failure. Vehicle dynamics
could also be adversely affected.
In order to minimise this effect, tire
pressures can be adjusted to
compensate before the start of the
journey. Alternatively, tire pressures can
be adjusted when the area of lower
ambient temperature is reached.
In this situation the vehicle must be left in
the ambient local temperature for a least
one hour before tire pressure is adjusted.
To compensate for colder ambient
temperatures, tire pressures should be
increased by 0.14 bar (2 lbf/in
2
, 14 kPa)
for each 10°C (20°F) decrease.
Note: Ensure that correct tire pressures
are maintained when moving to areas of
differing ambient temperature.
The Tire Pressure Monitoring system
(TPMS) may issue a warning if the under
inflation becomes significant. When
driving through variable climatic
conditions the TPMS warnings may be
intermittent.
In areas of extended high ambient
temperature, vehicle tires can be affected
by a softening of the tire side wall. If the
vehicle is stationary for long periods, the
effect is to slightly deform the tire at the
point where the tire meets the standing
surface. This is known as a flat spot.
This is normal tire behaviour, however,
when the vehicle is subsequently driven
vibration may be experienced from the flat
spot. The condition will steadily improve
with additional mileage.
In order to minimise this effect, tire
pressures can be adjusted to
compensate.
JAG0480G
JAG0481G