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Why Do My Tires Keep Going Flat or Losing Air?

There are many different reasons your tires may be going flat or losing air. These can include more obvious reasons such as an object that punctures the tire or tire damage but less obvious reasons such as improper inflation, weather, valve steam leakage, and sealing issues may also contribute.

Depending on which one of these things you experience and how severe the problem is will also determine the amount of time it takes for all the air to escape your tire.

It is not common to have to inflate your tire every day or once a week. Usually having to inflate your tires once a month can signal an issue under ideal circumstances.

How Often Should I Inflate My Tires?

checking tire pressure

Even though you should not necessarily have to re-inflate your tires every month, it is a good rule of thumb to check their pressure every month, especially when it gets colder.

Cold air causes air to contract and your tires to lose pressure as a result. This does not mean that you should not check them during the warm months of the year, nor does it mean that having to put air in your tires once a month is normal for you.

You know your vehicle the best, and if you have to start consistently adding air to your tires when the TPMS light comes on, you may want to investigate the possibility of a slow leak. Usually, when you have to start re-inflating your tires once every week or two, they need to be checked more thoroughly to see what is happening.

What Causes Air to Leak from Inflated Tires?

All tires lose air, regardless of how well they are mounted, how good the weather is, or how new the tires are. There is also a difference between this type of natural deflation and a slow leak.

Slow tire leaks happen over a short period of time compared to natural deflation, but they usually also happen much slower than a typical flat tire. There are several causes of slow leaks, all of which should be addressed when discovered. Any damaged or underinflated tire has the potential to affect the vehicle’s driving dynamics or cause a tire to rupture. Both of these situations can lead to additional vehicle damage or accidents if not repaired.

Weather

cold air tires

It is well-known that cold air causes tire pressure to drop. For every ten degrees drop in temperature, air pressure within a tire decreases one pound per square inch.

This means that if you inflate your tires to 35 PSI when it is sixty degrees outside, your tire pressure will have dropped to about 32 PSI in the morning when the temperature has dropped to thirty degrees.

A lesser thought-of tire pressure phenomenon is that the opposite happens in hot weather. Just as air condenses when it gets cold, it expands as it gets warmer. Just as many flat or deflated tires are seen during the summer as during the winter.

This is because the expanding air within the tire puts extra pressure on the tire, and can leak out of the seal. There is not much you can do about the weather, but the outdoor temperature is much less likely to affect your tires if you have a garage or other climate-controlled shelter or if you live in a climate that does not feature severe and frequent temperature swings.

Valve Stem Leak

Valve stem leaks are one of the most common reasons tires keep going flat. The valve stem is the part of the tire into which more air is allowed to be pumped.

As such, it is the easiest area for air to escape as well since it is the one area that is supposed to allow air to pass. If the valve stem is manufactured incorrectly or is damaged, it will cause leaking.

It can be damaged by numerous things including anything on the road that gets kicked up, a minor accident, or even during the mounting process.

Improper Mounting/Sealing

Improper mounting and sealing of a new tire are another one of the most common causes of slow leaks. If the tire sealant is not applied properly or a spot is missed, air will be allowed to escape.

Sometimes, the sealing itself is not the issue. If the wheel of a car is damaged or there is severe curb rash – when the rim of the wheel contains shallow damage – the seal may not be able to prevent air from escaping from the damaged wheel edge.

Slight Tire Damage

Damage to the tire itself is not as common of an issue for slow leaks. Tires are more resilient than they might seem, and any object that causes damage to a tire and doesn’t make it go flat relatively quickly would have to be very small and very rigid.

This does not mean that it cannot happen. Road debris is everywhere, and even something as small as a stone that is run over the correct way can cause damage. 

Age

cracked tires

Age is a factor in nearly everything because everything wears out. Tires are the same. As they become older, they crack and become hard. Because of this, they slowly lose their ability to hold air.

Just because a tire has plenty of tread, does not mean there may be another issue with them. This is especially true when buying used tires to try and save money. Tires can be expensive, and buying gently-used tires to try and save money is a common practice. Examining used tires for cracking and rotting is an easy way to avoid air loss and potentially dangerous driving conditions.

What Causes Flat Tires?

Most people think of getting a flat tire as a quicker event than a slow leak. Slow tire leaks sometimes take several days before being noticed as an issue. Flat tires usually take a day or less since the issue is usually a bit more severe. There are two main reasons vehicles get flat tires. 

Extensive Tire Damage

Extensive tire damage is most often caused by a larger than normal or sharper than normal piece of debris in the roadway that someone just happens to hit on the road.

The result is a puncture that can quickly drain a tire of air and requires the spare to be used. Extensive tire damage can sometimes be patched, but if the damage is extensive enough or the puncture is large enough, a new tire will be needed.

Blowout

A blowout is a sudden failure of the tire, and it can be caused by just about anything that has been mentioned thus far. They create dangerous situations and are a large reason that leaking tires, whether slowly or quickly, should be addressed as soon as possible.

Age, any kind of tire damage caused by a puncture, driving with low tire pressure, driving with over-inflated tires, improper tire mounting, stretched tires, and sealing can all cause a blowout. 

How Can You Prevent Tires From Going Flat or Losing Air?

There is not anything you can do to prevent a flat tire when it is caused by a random object that creates a puncture that deflates the tire. This is usually a random event that affects everybody at one point in time.

Fortunately, there are plenty of ways you can prevent tire leaking that will eventually lead to a completely flat tire. The best way to prevent this is by regularly examining your tires and monitoring their pressure.

Most vehicles have a tire pressure monitoring system that alerts the driver to abnormally low tire pressures, but this should only come on occasionally or when there is an issue.

Another thing you can do to avoid leaking tires is to find the cause and fix it. Obvious leaks and large punctures are identifiable by the sound of air leaving the tire.

Slow leaks are harder to diagnose and usually have to be found by a vehicle technician. Taking your vehicle to a mechanic is worth it though since so much is literally riding on your tires. Ignoring leaks can lead to potentially fatal consequences. 

Final Thoughts

Tires can lose air for multiple reasons. Tire damage, valve stem leakage, improper sealing and mounting, and age can all cause leaking tires. Of course, flat tires that deflate quickly are usually caused by random objects in the road that cause punctures. These are hard to avoid, but taking regular tire pressure measurements and visiting your mechanic if your tires start to leak is the best way to prevent and fix leaky tires. 

Shawn Furman
I have been a vehicle hobbyist for as long as I can remember as well as a freelance writer for the past three and a half years. My clients have included Vehicle Scene, Autolist, CarGurus, and now The Vehicle Lab. In addition to my current clients, I also maintain my own blog where I am able to share my knowledge and experience through vehicle reviews, car-buying guides, how-to guides, and list articles.
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