What is an important factor to consider when checking tire pressure?

When checking tire pressure, the ambient temperature at the time of measurement is a crucial factor to consider. Tire pressure can fluctuate significantly with changes in temperature. As the temperature drops, tire pressure typically decreases, and conversely, as temperatures rise, tire pressure increases. This is due to the physical properties of air; warmer air expands, leading to higher pressure, while cooler air contracts, reducing pressure.

For accurate tire maintenance, it is best to check tire pressure when tires are cold, usually before the vehicle has been driven for a significant distance. If tire pressure is assessed when the tires are warm—such as after driving—readings may be artificially inflated due to heat buildup from friction and movement. Therefore, understanding the relationship between temperature and tire pressure helps ensure that the readings reflect the true state of the tire, promoting safety, fuel efficiency, and tire longevity.