B. Tire Inflation
Measure your tiresí inflation pressure at least once a month, or when the
temperature changes abruptly.
Changes in ambient temperature cause changes in tire pressure, which is
particularly important in Canadaís climate where temperature swings of 15 to 20°C
are not uncommon. Every 5°C change in temperature results in about a 7-kPa (1-
psi) change in tire pressure, so a temperature drop of 15°C would result in
approximately 10 percent (21 kPa or 3 psi) under inflation.9
Additionally, tires are
permeable and losses of up to 14 kPa (2 psi) per month are not uncommon ñ more
in hot weather, as the pores in the tire material expand.10
Tire valves may become worn, and tire damage may result from rough roads, stones
and glass. All can result in pressure loss.
Canadaís cold winters present unique challenges for tire installers. For example, on
a ñ10°C day, the ambient air temperature in the service department may be 15°C, a
difference of 25°C. Therefore after the car leaves the shop, air pressure in the tires
will reduce because of the drop in temperature. Professional installers compensate
for the difference by adding the appropriate amount of additional air pressure. This
is often referred to as ìwinter air.î