Why Do Tires Lose Air? (Even When Not Punctured…)

Whether your tire is deflated or your check tire pressure light comes on, the tire with low pressure is the start of a mystery. If your initial investigation doesn’t yield any apparent reason for the air loss, the loss of air can be pretty confusing.

Tires can lose out for all sorts of reasons. Some of these reasons are benign, while others are more serious. Keep reading to learn how to tell the difference.

Why Do Tires Lose Air?

Even if your tire does not get punctured, tires lose air naturally as molecules penetrate the rubber. Even if your tire is perfectly intact, it will lose some air over time. Additionally, sometimes a tire will get a small pinhole puncture, which will leak air very slowly and is very hard to detect. 

There are plenty of other reasons tires can lose air, as well. Keep reading to learn about all the reasons tires may lose air, as well as what you can do about them.

Is It Normal for Tires to Lose Air?

All tires will lose air over time. Small amounts of air can pass through the rubber in the tire, which causes a loss of pressure over time.

Due to differences in construction, different tires lose air at different speeds. Usually, it’s around 1 to 3 PSI, however. If your tire’s air loss is within this range, then you have nothing to worry about.

While this number may seem small, it can add up substantially over time. For instance, the average tire needs 32 to 35 psi. If your tires lose three psi a month, then you can quickly halve your tire’s pressure.

Therefore, it is essential to check your tire’s pressure regularly. Even if there is no puncture, your tires are still losing air and will need to be refilled regularly. Without the proper pressure, tires are at a higher risk for blowouts.

Plus, tires that aren’t properly inflated require more energy to drive, which costs you more money in the long run.

You can slow down pressure loss by filling your tires with nitrogen. Because nitrogen molecules are larger, they don’t pass through the rubber as fast. Therefore, they often lose very little pressure over time.

Can Tires Lose Air from Sitting?

As we previously discussed, all tires lose air. The air simply moves through the rubber from the inside of the tire to the outside. Over time, this factor can lead to quite a lot of air loss.

This fact is true even if the tire is left sitting. Even if you aren’t driving the car, the air is still moving through the tires. Therefore, sitting tires will often lose air at a similar rate.

However, leaving a tire to sit for too long can cause increased air loss for a few different reasons.

When left sitting, the tire will start to deteriorate. As you probably know, the tires are holding up the whole weight of the car.

Usually, the tire is regularly rotated so that there isn’t a particular area carrying the brunt of the weight.

However, when the car is left sitting, all the weight is in one spot. Eventually, this will cause deflation. Flat, warped, and rotten tires will not hold in air at the same rate as healthy tires.

How Do I Stop My Tires From Losing Air?

How Do I Stop My Tires From Losing Air?

There is no way to stop your tire from losing air completely. No matter what, the tire will continue to lose pressure as air moves through the rubber.

As of yet, there is no way to prevent air from moving through the rubber completely. In many cases, quality tires lose air at a slower rate.

However, they do still lose it to some extent. Therefore, your best bet is to simply watch your tire’s psi and refill them as necessary.

Some drivers are switching to nitrogen to refill their tires. Because nitrogen molecules are heavier, they often pass through rubber slower than oxygen molecules.

Therefore, your tire’s overall air pressure will stay the same form longer.

However, this doesn’t prevent the problem completely. No matter what you use, your tires will still lose air and need to be refilled regularly.

For safety reasons, you should check your tire’s air pressure regularly. Don’t assume that they aren’t losing air.

Why Do Tires Lose Air in the Cold?

When it is hot, air molecules have more energy and move around more rapidly. No matter what type of molecule it is, heat equals more energy, which makes the molecules bounce around more.

When it is cold, molecules have less energy. While they never stop moving completely as a gas, they do slow down substantially.

The same is true for the air pressure in your tires. When it is hot, the air molecules in your tire move around a lot more, hitting the rubber quite a bit. When it is cold, they slow down.

Because they aren’t hitting the rubber of the tire as much, the pressure goes down.

In other words, it isn’t that the tire has lost air. Instead, the same amount of air is still in the tire. However, the tire may have a lower pressure because the air isn’t moving around as much.

Therefore, you may find yourself needing to add more air into your tire when the weather begins getting cold.

If you do add more air, be sure to check your tires when the weather warms up too. In some cases, the pressure may be a bit too high.

However, natural air loss in tires often balances out the pressure gain when it gets hot.

How Often Should You Put Air in Your Tires?

How Often Should You Put Air in Your Tires?

Because all tires naturally lose air, it is essential that you regularly fill them up with more air. Even if your tires don’t have a puncture, they need to be refilled regularly.

Generally, you should check your tire’s psi every month. Usually, tires lose about 1 to 3 psi during this time period. Often, that isn’t enough to call for refilling your tires. However, you’ll likely need to add air every two to six months.

For safety reasons, it is always better to check your tires more often than less often. After all, you don’t want to be driving around on tires that aren’t all the way inflated!

I recommend checking the psi even if you have sensors that are supposed to alert you to low tire pressure.

These sensors can break and not read the pressure properly. If your tire gets low and the sensor doesn’t go off, you can be in serious trouble.

Therefore, it is best to check manually from time to time as well.

On top of every month, you should also manually check the pressure when the tire pressure warning light comes on. Because tires lose pressure in the winter, these lights tend to go off the most in the winter months.

However, you should still check the tire pressure manually every time a light goes off.

To find out more, you might also read our posts on how long do run-flat tires, if you can replace run-flat tires with regular tires, and how common are flat tires.

Conclusion

Tires can lose air for all sorts of different reasons. Firstly, punctures and debris are obvious (and often the most dreaded) reasons.

However, tires do naturally lose air over time. The air molecules inside the tire will eventually work themselves out of the tire, leading to natural air loss. Still, this often occurs at a very low rate.

Cold weather can make it seem like the tire lost air. However, the actual amount of air doesn’t change on this occasion – just the amount of air pressure.

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