1.4Fundamentally, Why Is Temperature Monitoring Important?
The Pressure/Temperature Relationship
Tire manufacturers specify that tire pressures should be checked and adjusted when a tire is “cold”, but most people may not know why, or even what a “cold tire” is. The temperature of a tire actually has a significant impact on its inflation pressure.
According to tire manufacturers, a tire is considered to be “cold” when its temperature is 65°F (18°C). The inf lation values provided by vehicle manufacturers, fleet maintenance personnel, or
Air naturally expands when heated and contracts when cooled. Inside a contained vessel such as a tire, this expansion and contraction causes a change in contained air pressure. As a tire heats up, its pressure will naturally increase and as it cools down, its pressure will naturally decrease.
For example, a tire inflated to a CIP of 105 PSI at 65°F will increase in pressure to 125 PSI at 152°F and decrease in pressure to 97 PSI at 32°F. The SmarTire
Tire manufacturers never recommend inflating a tire to less than the specified cold inflation pressure. In extreme cases, the beads of a commercial tire can unseat if its pressure gets too low resulting in a catastrophic tire failure.
Always refer to the vehicle manufacturer’s recommendations for minimum cold inflation pressures.
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