HomeDo It YourselfDon't Get Deflated: Why Checking Your Tire Pressure Matters

Don’t Get Deflated: Why Checking Your Tire Pressure Matters

Tires are one of those items that you can easily forget about when getting your vehicle in tip top shape for that next big trip, or commute to work. Maybe you have just brought your vehicle out of storage.

Don’t let something as simple as a low tire ruin your day. Let’s learn more about one of the most simple maintenance items that every vehicle owner should know how to do. Checking their vehicles tire pressure.

Why do tires lose air pressure?

Fun Fact.

Did you know it is normal for all tires to lose air during their life?

It is true. All tires will leak over their lifetime, but not for the common reasons that you are thinking about. Those pesky nails, screws, stones, and other “sharp” items that seem to ruin your day.

Its caused by the very air that is used to inflate the tire.

The air inside of a tire consists of many small molecules, molecules that we cannot see with our eyes. These small molecules over time can “leak” out of the molecular structure of the rubber in the tire.

Tire tread of a tire with overinflated tire pressure

Molecular structure? What this means is the molecules of air are smaller than the rubber of the tire. Think of a really small mouse sneaking through a hole in the wall. This is what air is doing inside of the tire, looking for ways to escape the larger rubber molecules that create the tire. This process of the air escaping through the rubber of the tire is known as Permeation.

I understand permeation is a very technical term but results in some large issues with your vehicle if left unchecked.

If left unchecked permeation can cause the tire to lose over 1 psi per month. While not causing an issue immediately, if you are not checking your tire pressure often, it can result in issues.

The other issue your may find with your vehicle is the common leaky tire. This is where that nail, screw or possibly corrosion on the rim is causing the air to leak out of the tire.

These are the leaks that find your vehicle in the service center getting the tire fixed. Or worse, driving away at the back of the tow truck to get you back up and running.

There are ways to prevent this from happening. It will however, take some time and elbow grease to make sure your tires are always perfectly inflated.

Do I need to check my tire pressures?

Yes, you need to check your tire pressure often. Underinflated tires are not only a safety concern but tires that are not correctly inflated can also lead to other issues with your vehicle.

Tires that are not inflated to the correct pressure can cause excessive tire wear. Depending on if the tire is over or underinflated the type of tire wear you will notice can change.

For example, when the tire is underinflated (below pressure setting) the outside edges will contact the road surface. This causes the tires to wear along the outside edges of the tire.

close up showing outer tire wear of a tire with underinflated tire pressure

However, if the tire pressures are above manufacturers specifications, or overinflated. You will notice the center of the tire wearing prematurely.

This is caused by the tire ballooning causing only the center portion of the tread to contact the road surface.

An underinflated tire can cause many other issues, one of them that will drastically affect your pocketbook. An underinflated tire will cause multiple handling issues as well as a decrease in fuel economy.

The U.S Department of Energy has stated that when tires are inflated correctly it can increase your fuel economy by up to 3%. Because of the increase in fuel economy your vehicle will also produce less emissions as it is burning less fuel.   

The fuel economy increase is good news, with today’s fuel prices I think we could all use an increase in fuel economy, even a small increase. Checking your tire pressure really is a simple way to improve gas mileage.

Do I need to check pressures if my vehicle is equipped with tire pressure monitors?

I know what you are going to say. My vehicle has tire pressure monitors, I don’t need to check my tire pressures.

Sorry to break it to you, that may not be true.

Yes, you still need to check your tire pressures even if your vehicle is equipped with tire pressure monitoring technology.

Tire pressure monitors have a pressure range that the tire needs to be inflated to. If that range is not met, the low tire light will illuminate. This makes sure that the low tire light does not turn on and off multiple times during a day of driving.

This range may be 5 psi lower than the manufacturers recommendations. For example, if the manufacturer recommends a tire pressure of 40 psi, the low tire light will not illuminate until the tire has dropped to 35 psi or below.

So, a tire that is low in pressure and has not caused the low tire light to illuminate can lead to the affects that we discussed above. Increased tire wear, increased fuel consumption, and poor handling.

Also making sure that you check your tire pressures manually can allow you to notice if you have a problem with your tire pressure monitor system. If the light is illuminated and you checked and set all of your tire pressures, the system has detected a fault.

You will need to repair the problem with the low tire light system before the light will go off.

This is why it is always important to still check your tire pressures even if your vehicle is equipped with tire pressure monitors.

How often should I check my tire pressures?

I always recommend that you check your tire pressure once per month. As a good part of routine maintenance, you could combine this check with other items as well.

I would recommend that when you are checking your tire pressures once per month you take a good look at the tread and overall condition of your tires at the same time.

Check the following when you are checking your tire pressure.

  • Tread life remaining
  • Overall condition of the sidewall of the tires
  • Valve stem condition
  • Cracking or others signs of tire aging

If any problems are found during your inspection make sure you take care of them right away. Maybe it is time to replace your tires not just check the tire pressure.

How do I check my tire pressures?

Checking your tire pressure is one of the easiest car maintenance tasks that all vehicle owners can accomplish on their own with only a few simple tools.

However, there are a few things that you need to be aware of to ensure that it is done correctly.

First you need to know what the correct tire pressure is for the vehicle that you own. This can be found on the Tire and Loading information tag, this tag is generally located on the drivers door jamb. Among other items about seating capacity this tag shows the correct cold tire inflation pressures for the front and rear axle of the vehicle.

The tag will look like the one as shown in the image below.

Image of Tire and Loading Sticker

If this tag cannot be found, you can also find the manufacturers recommended tire pressure in the owner’s manual for the vehicle.

There is also a maximum inflation pressure on the sidewall of the tire. This is not what we are going to set the tire pressure too. This pressure is the maximum pressure that the tire is capable of holding, not the manufacturer of the vehicles recommended pressure.

If you noticed when checking the tag on the door jamb, it mentions the Cold Tire Inflation Pressures. The reason that you want to check your tire pressures when they are cold is as a tire is driven down the road the friction between the road surface and the tire creates heat.

Because of some interesting gas law that was discovered in the 17 or 1800’s (a topic you might find on a physics website), the heat that is generated from the friction causes the pressure inside of the tire to increase.

So, by making sure that we set the tire pressures at their cold recommended pressures we make sure that the tires are filled correctly as per manufacturers recommendations.

This is actually very easy to do. Simply check your tire pressures in the morning before you go driving anywhere that day. Waiting overnight will allow the tires to cool to the outside temperature that is present.

Use a Proper Gauge when checking your tire pressures

Most vehicle owners do not have an air compressor in their homes so you will find that you may end up using a local gas station to fill up and check your tire pressures.

Some gas stations will have a pressure gauge attached to their air nozzle that you can use to check your pressures as well. I would highly recommend that you do not use this gauge to check your pressures.

pressure gauge that is showing how to check tire pressure

As you can imagine, this community air filling station will see many people using these gauges through out the day. Not everyone knows how to treat these tools properly which can result in damaged tools that do not read accurately.

I would recommend purchasing your own “pencil type” pressure gauge from an online source or local reputable parts supplier.

These items do not generally cost much. You can place them in the glovebox of your vehicle so you know where they the next time you check your tire pressure.

By using your own pressure gauge, you will make sure that the gauge reads accurately when checking your pressures. This will also allow you to check your pressures at home and if the tires are within specifications, you can skip that extra trip to the gas station.

I hope this clears up some of the common questions that you may have regarding checking your tire pressures. If you have any other questions, drop them in the comments.

John Morris
John Morrishttps://autoknowit.com
John Morris is the technical editor for AutoKnowIt.com. His years of experience in automotive repair as well as an automotive professor have prepared him to ensure that even the most technical information is accurate and concise at all times.

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