Canada - Tire - Tire Inflation Pressure Compensation

Bulletin
L-TCI-3097

Issue Date
January 17, 2012

Market
Canada

Title
TIRE INFLATION PRESSURE COMPENSATION AND ADJUSTMENT

Service Category
General

Section
Pre-Delivery Service







APPLICABILITY:

INTRODUCTION:
The purpose of this bulletin is to provide a procedure to adjust tire pressure correctly when outside temperature is significantly colder than shop temperature.
Seasonal temperature change can dramatically alter tire pressure, which can cause the tire pressure warning lamp to illuminate.







WARRANTY INFORMATION:

Tire Pressure vs. Tire Temperature:
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 Toyota 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 4 hours and has been parked outdoors.

The TPWS MUST be initialized with the tire pressure marked on the vehicle placard. Tires are then adjusted according to the information in this bulletin to ensure that the TPWS light does not illuminate unnecessarily.







TIRE PRESSURE ADJUSTMENT:

Recommended Tire Pressure Adjustment:

NOTE
Use a high quality accurate tire pressure gauge, and check its accuracy regularly.

- Consider the difference in the air temperature in the workshop and the lowest ambient temperature you expect in the next few weeks (especially in winter).
- Use the chart (Figure 1) to compensate for temperature of the tires when you adjust the pressure.
- Use temperature compensation Example 1 for the spare tire.

Example 1: Temperature Compensation - "Cold" Tires
- The vehicle has been parked overnight outside shop (vehicle has "cold" tires) and tire pressures are set to 31.9 psi.
- Workshop temperature is 20°C (68°F), and expected lowest ambient temperature in the local area is to be -10°C (14°F).
- Subtract the expected lowest temperature -10°C (14°F) from the highest expected temperature 20°C (68°F) = 30°C (54°F).
- Using the tire pressure chart (Figure 1), find the intersection of the cold tire line at the point corresponding to 30°C (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

Example 2: Temperature Compensation - "Warm" Tires
- The vehicle has been driven to the shop on surface streets for about 30 minutes (vehicle has "warm" tires) and tire pressures are set to 31.9 psi.
- Workshop temperature is 20°C (68°F) and expected lowest ambient temperature in your area is to be -10°C (14°F).
- Subtract the expected lowest temperature -10°C (14°F) from the highest expected temperature 20°C (68°F) = 30°C (54°F).
- Using the Tire Pressure Chart (Figure 1), find the intersection of the warm tire line at the point corresponding to 30°C (54°F) and read off the value on the tire pressure change axis. In this case it would be about 6. 7 psi.
- The tires should be filled to:
31.9 + 6.7 psi = 38.6 psi

Example 3: Temperature Compensation - "Hot" Tires
- The vehicle has been driven to the shop on the highway for at least 60 minutes (vehicle has "hot" tires) and tire pressures are set to 31.9 psi.
- Workshop temperature is 20°C (68°F), and the expected lowest ambient temperature in the area is expected to be -10°C (14°F).
- Subtract the expected lowest temperature -10°C (14°F) from the highest expected temperature 20°C (68°F) = 54F.
- Using the tire pressure chart (Figure 1 ), find the intersection of the hot tire line at the point corresponding to 30°C (54°F), and read off the value on the tire pressure change axis. In this case it would be about 9.0 psi.
- The tires should be filled to:
31.9 + 9.0 psi = 40.9 psi