Happens every fall. One cold morning, I go to start the car, and the tire inflation alert on my dashboard lights up. Something to do with molecules. According to United Tire and Service News,
"Air contracts when the temperature drops—and the air inside your
tires is no exception. The reason this occurs has to do with the speed
at which air molecules move. The lower the temperature, the slower they
become. Slow-moving molecules are smaller, take up less space, and don't
push up against the walls of your tires with as much pressure.
So, no, your tire pressure isn't low on cold days because your
tires haven't technically lost air. (In fact, your tire pressure will
likely go right back to normal the minute it gets warmer.) It's
dangerous to drive on even mildly deflated tires, though. It can damage
your tires, as well as potentially cause an accident, so always err on
the side of caution and give your tire pressure a quick check to be
sure. If they genuinely need more air, go ahead and top them off to be
on the safe side."
