Proper Tire Pressure And How To Check Tires

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As you know, tires are filled with air, but surprisingly few people have a correct understanding of “proper air pressure and inspection methods.

You may not be aware of your tires on a regular basis, but tire pressure management is more important than you think.

Insufficient air pressure not only prevents tires from performing properly but can also lead to tire damage and accidents.
In this article, we will discuss the proper tire pressure and how to check it.

About Tire Pressure

As mentioned in the introduction, tire pressure is very important for a vehicle. Without proper air pressure, tires may not perform as well or tires may be damaged.

Also, even once the tires are inflated to the proper pressure, they will continue to lose air. Therefore, regular inspections are essential. Let’s take a look below at the proper tire pressure and the reasons why tires lose air naturally.

What Is The Proper Tire Pressure?

The correct tire pressure is, in other words, the designated air pressure set by the manufacturer for each vehicle model. The designated air pressure is indicated on a sticker near the driver’s door or on the back of the fuel filler lid.

Since the proper air pressure varies depending on the weight and characteristics of the car, the designated air pressure varies for each car model even if the tires are the same size. When the same size tire is used on the same car, the specified air pressure is the same regardless of the brand of tire.

If you check the air pressure frequently, it is OK to set the air pressure exactly to the designated pressure, but it is recommended to set the air pressure a little higher within the range of 0 to +20 kPa to allow for natural air loss.

Tire Air Naturally Deflates

You may be thinking, “How can a tire naturally deflate if there is no flat tire?” You may wonder, “How can a tire naturally lose air if there is no flat tire?

Tires are made of rubber, and air molecules can pass through the rubber. Therefore, air naturally leaks out little by little.

This can be easily understood by imagining a balloon. A balloon filled with air will naturally deflate after a few days. The same thing happens with tires.

Incidentally, it is said that the air pressure that decreases in a month due to natural air leakage is 5 to 10% of the total air pressure and that about 41% of cars are underinflated.

The 5-10% of the total pressure loss means that, for example, a tire with an air pressure of 200 kPa will lose 190-180 kPa after one month.

What Happens If The Tire Pressure Is Low?

Low tire pressure can be very dangerous, causing handling instability, punctures, and bursts. Let’s take a closer look below.

Fuel Consumption Will Deteriorate

As air pressure decreases, tire deflection increases, and rolling resistance increases. Increased rolling resistance = loss of power, resulting in lower fuel economy.

To give an idea of how much fuel consumption will deteriorate, for example, if the air pressure is lowered by 50 kPa in a car with a specified air pressure of 200 kPa, fuel consumption will deteriorate by approximately 4% in suburban areas and by approximately 2% in urban areas.

Handling Becomes Unstable

As tire pressure decreases, tire sag increases and handling becomes unstable. Not only that, but the vehicle is more likely to be caught in ruts and uneven road surfaces.

Increased Risk Of Punctures

Driving on highways with underinflated tires causes the “standing wave phenomenon,” in which the tire deforms like a wave.

The standing wave phenomenon occurs when the tire deflection becomes too large, causing the tire to deflect continuously, resulting in a wavy appearance. If the tire is driven as it is, there is a risk of bursting.

In addition to the above phenomena, “heat separation” and “breathing CBU” can also occur. Heat separation is abnormal heating caused by insufficient air pressure. Eventually, the heat can cause bursts.

Bleating CBU is a phenomenon in which the tire deflects abnormally due to underinflated air pressure, causing the internal carcass cords to break. This can also cause a puncture or burst.

Both cases are extremely dangerous, so be sure to check the air pressure, especially before driving on highways.

Loss Of Grip

Tire pressure that is either too low or too high will reduce grip. In other words, balance is important.
If the air pressure is too low, the tire will not be able to press down on the ground from the inside and the grip will be reduced.

If the air pressure is too high, the center of the tire will expand and the contact area will become narrower, reducing grip.
Since reduced grip increases the risk of slipping, it is advisable to adjust the tire pressure to the specified pressure, neither too high nor too low.

Shortened Tire Life

Insufficient air pressure causes the phenomena described in the “Increased risk of punctures” section, so even if a puncture or burst does not occur, the tire will gradually become damaged.

Excessive deformation of the tire leads to deterioration of the rubber and carcass, so even if it is not immediately apparent, the life of the tire is gradually being shortened.

It is important to check the air pressure without fail because it is the best way to extend the life of tires and prevent accidents.

How To Check Tire Pressure

Here we will explain how to check the air pressure in your tires. Once you have learned how to check the air pressure, it is easy to do, so please refer to the following to master the procedure.

When checking air pressure, use an air compressor available at gas stations or car accessory stores, and refill the air at the same time. If you have a compressor at home, you can of course use it.

There are two types of air compressors available at gas stations: tank type and stationary type, and we will explain how to use each type.

When Checking Air Pressure With The Tank Type

First, remove the tank from the stand and measure the air pressure by pressing the nozzle of the air gauge against the air valve on the wheel.

At this time, be careful that the tip of the nozzle is not firmly attached to the valve, otherwise, air will leak out and accurate air pressure measurement will not be possible.

If the measurement results show that there is not enough air, hold the grip on the air gauge side to add air. Fill the valve with air until the specified air pressure is reached. If you overinflate, simply press the air release button on the air gauge.

Basically, as described above, you can adjust the air pressure by operating the air gauge only, but there are some models that have an air pressure adjustment function on the tank itself.

In such cases, the air pressure is adjusted by pressing the button on the air tank. The plus button is for inflating and the minus button is for deflating.

A tank-type inflator cannot be inflated if the air in the tank runs out. If the air has run out, it can be filled again by setting it on the stand where it was placed.

When Checking Air Pressure With A Stationary Type

In the case of a stand-type stationary air inflator, the method of operation differs slightly from that of a tank-type inflator. First, turn the dial next to the meter and adjust the needle on the meter to the specified air pressure.

After adjustment, press the end of the hose against the tire valve. When the hose is connected, the air will automatically inflate with a “chirping” sound. When the sound stops, it is a sign that the air pressure has reached the level set by the dial.

Incidentally, stationary inflators generally do not have a button to release the air. If you overinflate, press the valve bug to manually release the air.

Points To Keep In Mind When Checking Tire Pressure

When checking tire pressure, there are a few precautions that should be observed.

Air Pressure Should Be Adjusted Within The Range Of 0 To +20 KPa Of The Specified Air Pressure

Do not go below the specified air pressure, taking into consideration natural air leaks and driving on highways.

Inspect Tires When They Are Cold

Since the air inside the tire expands thermally as it warms up from driving, it is impossible to accurately measure the air pressure immediately after driving. Therefore, when measuring the air pressure, do so when the tires are cold.

Don’t Forget To Check The Air Pressure In The Spare Tire

It is easy to forget that a spare tire exists, but it is useless if it is deflated and cannot be used in an emergency.
The designated air pressure for the spare tire is indicated on the side of the tire, so adjust the air pressure accordingly.

Check For Air Leaks From The Valve And Wheel Deformation

When we talk about checking air pressure, we tend to focus only on the tires, but it is also important to check for air leaks from the valves and deformation of the wheels at the same time.

Since valves are also made of rubber, air leakage may occur due to deterioration. To check for air leaks, pour soapy water on the valve and see if bubbles form.

Wheels should be visually checked carefully for distortion and cracks. In particular, areas, where the paint is peeling off, should be checked carefully as distortion or cracks may be suspected.

Specified Air Pressure Is Not Necessarily The Same For Front And Rear Tires

Basically, the specified air pressure for front and rear tires is the same, but please note that the specified air pressure for front and rear tires may differ depending on the type of car.

In particular, imported cars often have different air pressures specified for front and rear tires, so check carefully.

Low Flat Tires Make It Difficult To Detect A Loss Of Air Pressure

Since low flat tires do not flex easily, it is difficult to visually detect a loss of air pressure. Instead of judging by appearance, be sure to use an air gauge to accurately measure the air pressure.

Also, low flat tires contain less air than normal tires, and the tire strength is compensated for by the air pressure. Therefore, it is necessary to adjust the air pressure to be higher than the specified pressure.

If you are unsure of the proper air pressure, consult the staff at a gas station or tire store.

How Often Should Tire Pressure Be Checked?

Ideally, tire pressure should be checked once a month. Regular monthly air pressure checks will keep your tires in the best condition.

Monthly checks will also help detect problems such as flat tires at an early stage. Depending on the monthly mileage, if the air pressure is significantly lower than last month, there is a good chance you have a flat tire.

If you find it difficult to check the air pressure every month, you can use a sensor or other convenient item that monitors tire pressure. This is very convenient because you can constantly monitor the air pressure from inside the car.

Is Nitrogen Gas Filling Effectively?

You may be advised to fill your car with nitrogen gas at gas stations, but what are the benefits of filling it with nitrogen instead of regular air? The following are some of the advantages.

Less Prone To Natural Air Leakage

As explained earlier, tires naturally lose air because oxygen molecules are smaller than rubber molecules in tires.

Nitrogen gas has larger molecules than oxygen, making it more difficult to pass through the tire rubber. This means that the amount of natural air leakage is reduced. The amount of natural air pressure loss in a tire is about half that of air.

Less Likely To Change Air Pressure Because It Does Not Contain Water

Air contains trace amounts of water molecules, but nitrogen contains no water. Therefore, nitrogen does not expand thermally, and its air pressure does not change easily due to temperature changes.

Because it is an inert gas that does not contain oxygen as well as water, nitrogen also serves to protect tires and wheels from oxidation. It also has the effect of preventing the spread of fire from the oxygen in the tires in the event of a car fire.

Increased Quietness

Because nitrogen has a low ability to transmit sound, it has the effect of reducing the noise transmitted from the tires to the interior of the car.

Although filling tires with nitrogen gas has these advantages, it also has disadvantages such as limited space for filling and high cost.

Another disadvantage is that once nitrogen is added to a tire, the benefits of nitrogen diminish when the tire is refilled with air.


How was your experience? It is easy to forget to check tire pressure, but tires can only perform to their full potential when they are inflated to the correct pressure.

Insufficient air pressure not only reduces performance but can also be the cause of problems such as punctures and bursts.

Please refer to the information explained in this article and be sure to check the air pressure regularly, once a month.