Seasonal temperature change can dramatically alter tire pressure, which can cause the tire pressure warning lamp to illuminate. Tire temperature is dependent on “cold” tire pressure, driving distance and speed, ambient temperature and road surface temperature. As the temperature of the tire changes, air in the tire expands and contracts, changing the tire’s air pressure. The cold tire pressure for all models will vary and will need to be adjusted accordingly.
“Cold” tire pressure, as shown on the tire pressure label on our vehicles, is generally considered to be the pressure in a tire that has not been driven in the past four hours and has been parked outdoors.
The tire pressures must be set with the tire pressure marked on the placard. Tires are then adjusted according to the current conditions to ensure that the TPMS light does not illuminate unnecessarily.
If a vehicle has been parked overnight outside shop (vehicle has “cold” tires) and tire pressures are set to 31.9 psi. Shop temperature is 68°F and expected lowest ambient temperature in the local area is to be 14°F. Subtract the expected lowest temperature (14 F) from the shop temperature (68°F) = 54°F.
Using the tire pressure chart, find the intersection of the cold tire line at the point corresponding to 54°F and read off the value on the tire pressure change axis. In this case, it would be about 4.9 psi. The tires should be filled to: 31.9 + 4.9 psi = 36.8 psi.