Why do tires lose air? Here’s the reason

The reasons tires lose air can be divided into two main causes: normal (osmosis/permeation, temperature change) and abnormal causes (damages in wheel parts and tire).

Abnormal causes

Damaged wheel elements

This damage, creating holes on tire casing for air to leak through, can either be from a valve stem failure or a bent wheel.

Bad valve stem

Bad valve stem

Bad valve stem

Valve stems can deteriorate or wear out over time. Or it can easily crack as it exposes out of the tire. Just like that, the air slowly and eventually leak out, causing your tire to deflate as time passes.

Sometimes, over-tightening the valve stem can also be a factor that accelerates the speed of deterioration, which leads to leaked air.

Bent or Damaged Wheel

Bent wheel release air

Bent wheel release air

Wheel, specifically those made from aluminum or magnesium alloy, can ultimately suffer from rust and corrosion. This might cause the wheel to lose its round shape, especially if the corroded rim is on the edge that the tire is mounted.

In some cases, bent wheels after road hazards might also be another reason to contribute to air leaking, as it can cut the bead or causes uneven surfaces.

A wheel that lost the round shape will not be able to hold the tire tightly onto it. In this way, the bead area will have spaces for air to leak out, resulting in deflated tires over time.

Tire damages

Regardless of the size of the damaged area, it can causes tires to lose air directly. Here are some of the most common damages of a tire.

Nails

Nail in tire

Nail in tire

Bumping into nails on roads is a prevalent minor incident that everyone will encounter at least once. The nails can make tires lose air at the rate of 2 to 3 psi each day passing by. If not found soon, they might remain in the tire and eventually lead to air leaking out.  

Although the amount of air leaked here is insignificant, it still needs to be removed or else your tire will deflate sooner or later.

Bead damage

Bead chunking

Bead chunking

Any impaired sealing surface between the metal wheel and rubber part can lead to tire bead damage. Consequently, bead chunking happens. This is the situation when a piece of the tire bead tear and form into a small size perforation, and open spaces for air to leak out.

In some cases, old tires' weakened rubber or deteriorated elasticity can also cause the seal to break, damaging and deflating the tires.

Other damages caused by road hazards

Sudden hits on road curbs or potholes can cause significant damages to your tires. After any small incidents, check your tires as the sidewalls can flex, resulting in bulges and letting the air to leak through. Moreover, there can be punctures, which will surely open spaces to release air pressure.

Normal causes

Osmosis (Permeation)

Osmosis in tire

Osmosis in tire

Osmosis, as known as Permeation, is the ability of air passing through the tire rubber, at the rate ranging from 1-3 psi per month. Depending on the model of the tire and type of rubber used, the amount of air loss can be different.

While losing 1-3 psi each month might seem insignificant, it can really deflate the tire after a while. After half or a year, you'll already have a flat tire. Thus, make sure to check your tires regularly, and have it re-inflated from time to time.

Temperature change

Do you know tire air pressure can change accordingly to the temperature? A tire loses 2% air pressure every time a 10°F-drop happens. In contrast, it rises by 2% whenever the temperature increases by 10°F.

In this way, given a dramatic change in temperature, even brand new tires can result in leaked air.

Locating the leak air

So now that you know the answer to your question of "Why do tires lose air?", how can you find the exact location of where the air leaking is a different story.

Here we have compiled some ways you can locate the spot.

By feel or sound

In some most common leaked air tires, the easiest and most popular way car owners use to find the leaked spot is by sound or feel.

You might hear a hissing sound or touch the tire part by part to feel where the air is released.

Use soap water

Bubbles in leaky part

Bubbles in leaky part

Use any soap water to spray into the entire tire and edges. Bubbles will appear where the leak is. You can spray the valve stem first, to check if the air pressure is leaking through a poor valve stem.

Dip the tire into water

Detach the tire from the car and put it into water. You will see small bubbles released. That's where the air can leak. Once done with one side, turning the tire over to make sure you have it entirely checked.

Frequently Asked Question

Question: What is the right tire pressure?

Answer: The recommended pressure for tires usually ranges between 30 and 35 psi.

For the specific psi for your car, you can find the specifications for tire pressure in the following places:

  • In the vehicle owner's manual
  • In label stickers posted on the door jamb of the driver's side
  • Labels on the fuel door or console, or even on the trunk lid.

Question: How often should I check on my tire pressure?

Answer: Experts often advise to check your tire pressure at least once every gas fill-up, or once a month. However, it would be best if you also had tire pressure check every time there is a change of 10 degrees in the temperature.

Final words

With our article, we hope you now already found the answer to the question of why do tires lose air. Or you also know how to fix and avoid the tires losing air over time. Have your vehicle checked regularly and maintain the right amount of air pressure, and you'll never worry about damages.

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