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How to Check Tire Pressure

Dan Ferrell writes about do-it-yourself car maintenance and repair. He has certifications in automation and control technology.

Improper tire inflation pressure can contribute to tread uneven wear.

Improper tire inflation pressure can contribute to tread uneven wear.

Checking tire pressure regularly and maintaining correct inflation pressure can prevent:

  • improper inflation due to changes in temperature and pressure loss
  • excessive tire heat
  • tire squeal
  • hard steering
  • tire bruising
  • accelerated tire wear
  • increased fuel consumption
  • poor handling and road grip
  • serious road accidents

As temperature changes, tire pressure changes. Usually, your tire loses about 1 psi (pound per square inch) for every 10F degrees change. Add this to the 1-2 psi a tire loses every month, then you can see how your tires can start wearing faster if they remain underinflated for a long period. Your fuel economy also drops, since your tires now have to overcome increased resistance while rolling down the road. And vehicle handling suffers, especially on wet roads.

Do I Need to Check Tire Pressure Even with a TPMS Installed?

Since September 2007 in the United States, all passenger vehicles, trucks and multipurpose passenger vehicles under 10,000 pounds of weight come equipped with a Tire Pressure Monitoring System (TPMS).

The system monitors air pressure level for each tire and alerts you when one or more of your car tires drop at least 25 percent below the recommended air cold-inflation pressure. That's a loss of 8 psi on a tire with a recommended pressure of 32 psi. However, even a difference of 5 psi from the correct level can affect vehicle handling, and your safety, under certain road conditions. So, you still want to watch your vehicle tires' pressure.

Index

I. How Do You Know Your Tires Have Incorrect Tire Pressure?

II. Tire Pressure Gauges

III. How Much Air Pressure Your Tires Need?

IV. When is the best time to check tire pressure?

V. Check Tire Pressure

VI. Inspect Your Tires

VII. What are the benefits of checking tire pressure and physical condition regularly?

VIII. How Often Should You Check Your Tires?

Always inflate tires when cold and to manufacturer specifications.

Always inflate tires when cold and to manufacturer specifications.

I. How Do You Know Your Tires Have Incorrect Tire Pressure?

Unless your tire is visibly in need of air, it's hard to tell just by looking at them. You need to use a tire gauge to actually get each tire pressure. Other than that, there are several signs that can alert you about tire pressure issues:

  • an overinflated tire will tend to bounce over road imperfections: uneven road surfaces provide a bumpy ride.
  • an underinflated tire tends to produce a squealing sound when turning a corner.
  • uneven inflation among tires produces steering wheel pull.

A few pounds under or over the recommended inflation pressure can go unnoticed for a long time--especially on radial tires, which can hide low inflation pressure. Underinflation allows the tire to flex more and build up extra heat. Overinflation reduces the tread area in contact with the road and resistance to damage.

And you may not become aware of these issues until your tires begin to show signs of premature wear.

But you can prevent improper inflation and its negative domino effect by checking and inspecting your car tires regularly. With a simple procedure you can correct pressure and check for revealing signs of potential trouble. Best of all, it only takes a minute or two.

But first, you'll need a tire pressure gauge.

Use a quality tire gauge to check tire air pressure.

Use a quality tire gauge to check tire air pressure.

Tire Pressure Gauges

A tire pressure gauge is a common tire service tool. You'll find it at auto parts stores, auto and tire dealerships, and most department stores. Tire pressure gauges come in pencil (mechanical or internal slide), dial, and digital configurations. Regardless of configuration, make sure to use a quality tool. You can find relatively inexpensive, quality tire gauges like this one from Amazon.

Tire Safety

III. How Much Air Pressure Do Your Tires Need?

Your car manufacturer gives you the correct tire inflation level on a sticker or placard found on the driver side doorjamb or inside the glove compartment; your car owner's manual also has this information.

But you can also get a close approximation to the recommended pressure. The tire's sidewall gives you the maximum inflation pressure for that particular tire. It'll say something like:

"300 kPa (44 psi) MAX. PRESS"

The recommended inflation pressure falls between 1 and 3 pounds below this maximum pressure. For example, if the maximum inflation pressure indicated on the sidewall says 35 psi, your recommended inflation pressure will fall between 34 and 32 psi. This allows for internal heat buildup as the tire's surface rubs against the road. So, if you inflate this particular tire to 32 psi, you'll be at a safe inflation pressure.

IV. When Is the Best Time to Check Tire Pressure?

  • Check tire pressure early in the morning before you drive the car and the tires are cold.
  • If you just drove your car for a mile or more, allow the tires to cool for about two to three hours to allow tire heat to dissipate.
Keep a quality tire pressure gauge on hand to check your tire pressure at least once a month.

Keep a quality tire pressure gauge on hand to check your tire pressure at least once a month.

V. Check Tire Pressure

Now, armed with your tire gauge and the recommended inflation pressure information, it's time to check your car tires' current pressure.

  1. Look for the stem valve on the tire and unscrew the cap.
  2. Press your tire pressure gauge squarely onto the valve stem. If done properly, you will hear a bit of air come out as you press the gauge against the valve. If the hissing sound doesn't stop, you are holding the gauge at an angle and allowing air to escape the tire. Just remove the gauge and try again.
  3. Holding the gauge against the valve, read the pressure indicated on the dial, readout or graduated stick that slides out the bottom of the gauge, depending on the type of gauge you are using.
  4. Compare your gauge reading to the recommended pressure and make a note of the number of pounds the tire will need to bring it up to the recommended pressure level, if necessary.
    • If pressure is over the recommended specification, use the gauge to release air pressure from your tire by slightly pressing the gauge fitting against the air valve.
  5. Replace the valve stem cap.
  6. Check the rest of the tires' pressure, including the spare tire.
  7. Then, head over to the gas station to adjust air pressure as necessary.
Uneven wear can signal mechanical problems.

Uneven wear can signal mechanical problems.

VI. Inspect Your Tires

While checking tire pressure, take a moment to inspect each tire:

  1. Run your hand along the tire's sidewall and tread surface and feel for distorted areas like:
    • bulging (on the sidewall)
    • cupping (over the tread surface)
    • cuts
    • cracks
    • missing chunks of tread

    If necessary, take your car to a tire shop to determine the source of damage and fix potential problems.

  2. Check the tread area for abnormal wear patterns. For example:
    • between the center and outer tread areas

    Uneven wear may be an indication of problems with inflation, alignment, wheel balancing, or the suspension.

  3. Then, check for tire wear.
    • Locate the small wear bars that run across tread blocks. On some tires, the wear bar will show up as a wide, solid rectangle running across a section of the tread area.
    • Tread block height should be taller than the wear bars.
    • If the tread surface has reached the same level as the bars, you'll need to replace the tire soon.

Watch the next video to get a visual rundown of an inspection procedure, including location of the wear bars.

Proper inflation and regular tire condition checks can help prevent serious accidents.

Proper inflation and regular tire condition checks can help prevent serious accidents.

VII. What Are the Benefits of Checking Tire Pressure and Physical Condition Regularly?

Inspecting tire pressure regularly and maintaining correct inflation pressure offers several benefits:

  • A longer service life for your tires
  • Better gas mileage
  • Better engine performance (and lower emissions)
  • Improved car handling
  • Shorter stopping distance
  • Improved ride
  • Better heat buildup control
  • Proper tire deflection over road irregularities
  • Better resistance against damaging potholes

The next video shows how to properly inflate your tires at the gas station.

VIII. How Often Should You Check Your Tires?

Automotive manufactures recommend drivers to check tire pressure and tire physical condition at least once a month, a period in which a tire may lose 1-2 psi. And up to 4 psi during the fall or winter. Besides, tire and vehicle mechanical problems can develop without warning. Spotting uneven wear during your inspection can alert you of this. So inspecting your tires regularly can give you time to correct potential problems at a much lower cost.

This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.

© 2014 Dan Ferrell

Comments

John Dove on May 14, 2019:

Hi Dan--

I like your very thorough article. You brought out some great tips. Many people ignore tire pressure until the dashboard "tire pressure" alert. Also, don't forget about the spare tire. I bet most people haven't ever checked spare tire pressure until there's a problem -- aka flat tire.

MyRouteOnline Route Planner from USA on April 14, 2015:

Could have helped this police officer in Sydney, when crashed into a car on red light - http://www.9news.com.au/national/2015/04/14/09/34/...

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