It’s a telling sign every year that colder temperatures have arrived: your tire light pops on as you’re shuttling the kids to school or heading into work.
Why does this happen and what does it actually mean for your tires? We dive into the details below:
Key Points
- When temperatures drop, the density of the air in your tires increases, so it doesn’t take up as much space.
- As the air becomes more dense, the pressure in your tires fall, triggering the light.
- After driving around for a bit, the air temperatures in the tire warm and the pressure rises again. This could cause the light to disappear after being on the roads for a little while.
- AAA recommends that tire pressures should be checked at least once a month so that they can be adjusted as necessary.
Cold air is more dense
The explanation behind what is happening to the air in your tires when cold weather arrives can be explained by the relationship between temperature and density.
Density, which is the mass of a substance per unit volume, and temperature have an indirect relationship. Thus, when the air temperature decreases, density increases and vice-versa.
When a fall cold front ushers cooler air into South Central Texas, temperatures drop, especially in the mornings. This causes the air in your tires to become more dense, meaning it takes up less space in your tires since the molecules aren’t moving around as fast as they would if warmer air was in place. This in turn reduces the pressure in your tires, causing the light to pop on.
After you start driving around for a bit, the rubber starts to warm, lowering the air density and increasing the pressure in the tires. This is why your tire light might turn off after driving on the roads for a little while.
According to Goodyear, for every 10 degrees the temperature drops, tires will drop one to two pounds of pressure.
Check your tire pressure
AAA recommends that even if your car has a tire pressure monitoring system (TPMS), your tire pressures should still be checked monthly so that you can adjust them as necessary.
This is because the range in which your tire pressure light comes on is way lower than the pressure threshold in which your tires should ideally be kept on a day-to-day basis.
Monthly tire pressure checks will also give you a reason to look for cracking or extra wear on your tires.
Other reasons why your tire light may be on
According to AAA, there are a few other reasons why your tire light might pop on:
- Underinflated tires
- Overinflated tires
- A faulty tire pressure sensor
- Under or over inflated spare tire (if it has a sensor)
In most cases, the tire pressure light comes on when the pressure is 25% under or over the threshold set by the manufacturer.
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