Why cooler weather can lead to low tire pressure for your car

If you turned on your car this morning, you may have noticed a low tire pressure warning pop up on your dashboard. Don't worry, because this sudden change in tire pressure could just be due to the colder air that was seen this morning.

Temperatures were measured in the mid 40s this morning, which is almost 20 degrees cooler than the temperatures that Central Missouri was experiencing just a week ago during the morning hours. This is thanks to a cold front that passed through the area Monday, which put Missouri back in northerly flow. This has led to mornings in the 40s and afternoons in the low 70s.

But how does this impact the pressure in your car's tires? Well, temperature is a direct measure of how energetic the surrounding air molecules are in an area. Warmer air means more energetic air molecules that are less dense and move more frequently. This causes higher pressure in the area where this warmer air is residing.

Colder air means less energetic air molecules that are denser and don't move as frequently as warmer air molecules. This lack of movement and energy causes the molecules to contract and condense, so they do not take up as much space in the area they are in. Pressure then lowers due to the lack of movement and space being taken up by the molecules.

So on hot summer days, the air molecules that are inside a car tire are more tightly packed together, especially because the hotter weather causes the molecules to expand. This can lead to an increase in tire pressure. Another way an increase in tire pressure can occur, even with cooler temperatures, is long drives. This is because the air molecules inside the tire begin to heat up and expand as the tires work to keep the car moving.

On days like the one we had this morning, the opposite occurs. The air molecules that are inside the tire aren't as energetic due to the cooler temperatures, so the molecules contract. As the molecules contract, the amount of pressure that is being put on the tire decreases, so the overall tire pressure decreases as well. This is why, on those cold fall mornings as you turn on the car, you may get a warning that the pressure in your tire is low.

For these situations, all that is needed is for a little extra air to be added to the tire before making your daily commute. Once temperatures warm up in the afternoon hours, that air will get warmer and expand, leading to higher pressure returning to the tire that was once lacking it.