BENDIX BW2920 manual Fundamentally, Why Is Temperature Monitoring Important?

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 industry-published load inflation tables are called ‘Cold Inflation Pressures’ (CIP) because they represent the correct amount of pressure a tire should be inflated to when it is “cold”. The reason that tires have cold inf lation pressures set at specific temperatures is because a tire’s pressure will change relative to its temperature.

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 Trailer-Link™tire monitoring system considers these changes in temperature and pressure as part of normal operation and adapts accordingly to provide more accurate information while helping to prevent false alerts.

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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