How to measure tire tread depth with a penny


How to Check Tire Tread Depth: The Penny Test

When it comes to checking tire tread, there are a number of methods that can help you know if it’s time to replace a tire. Heavily worn tread will prevent a tire from performing as designed and can lead to unsafe driving conditions. One of the simplest, most common ways to check tread depth requires nothing more than a penny and a few moments of your time.

THE PENNY TEST

In the United States, tire tread depth is measured in 32nds of an inch. New tires typically come with 10/32” or 11/32” tread depths, and some truck, SUV and winter tires may have deeper tread depths than other models. The U.S. Department of Transportation recommends replacing tires when they reach 2/32”, and many states legally require tires to be replaced at this depth.

The idea of the penny test is to check whether you’ve hit the 2/32” threshold. Here’s how it works:

    Place a penny between the tread ribs on your tire. A “rib” refers to the raised portion of tread that spans the circumference of your tire. Tire tread is composed of several ribs.

    Turn the penny so that Lincoln’s head points down into the tread.

    See if the top of his head disappears between the ribs. If it does, your tread is still above 2/32” , If you can see his entire head, it may be time to replace the tire because your tread is no longer deep enough.

    When performing the penny tire test, remember not only to check each tire, but to check various places around each tire. Pay special attention to areas that look the most worn. Even if parts of your tread are deeper than 2/32”, you should still replace the tire when any areas fail the penny test.

    Consistent wear around the whole tire is normal, but uneven tread wear could be a sign of improper inflation, wheel misalignment, or a variety of other things. If you see uneven tread wear, you should have a technician inspect your vehicle.

    OTHER WAYS TO CHECK TIRE TREAD

    TREAD DEPTH GAUGE

    A simple way to check your tire tread depth is by using a tread depth gauge. You can find tire tread depth gauges at your local auto parts store. There are many models available, but an inexpensive simple graduated probe gauge will work just fine. All you have to do is stick the probe into a groove in the tread and press the shoulders of the probe flat against the tread block and read the result. All gauges should measure in both 32nds of an inch and millimeters.

    TREAD WEAR INDICATOR BARS

    Another indicator of worn out tread already lives in your tires themselves. Every performance, light truck, or medium commercial tire comes equipped with indicator bars (or wear bars) embedded between the tread ribs at 2/32”. They’re there to help you monitor tread depth and make decisions about tire replacement. Just look to see if the tread is flush with the indicator bars. If they are, it’s time to replace the tire.

    DON'T WAIT UNTIL IT'S TOO LATE

    While the penny tire test does deliver on what it promises – indicating whether tread has reached the legal limit – it may not be the best indicator of whether your tires are safe for the road. Tire performance can diminish significantly before your tread hits 2/32”. Even though the law deems fit for safe driving may not prevent you from hydroplaning or losing control in rainy, slushy conditions. If you think your tires may be close to needing replacement, have them checked out by a licensed mechanic.

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    Tires

    • Feb 12,2018

    When your tire treads wear thin, you could be in for a slippery ride—literally. Luckily, you can spot dangerous tread depth using only a penny, and Honest Abe’s face! The penny test is quick, easy, and can help you know exactly when to replace tires.

    The Penny Test

    To check your tread depth, you don’t need any fancy tools or expert knowledge. Grab a penny, and you have everything you need!

    1. Place your penny into a tread groove upside down. In other words, your penny should be going into the tread headfirst!
    2. Examine the part of the penny that’s showing. If you can see the top of Abe’s head, your tread is shallow.
    3. Repeat the penny test in several grooves of your tires. If you can always see the top of his head, your tire is worn and it’s time for a replacement!
    4. For reference, the distance between the top of a penny and Abe’s head is about 2/32nd of an inch. If you can see the top of his head, your tread is less than 2/32nd of an inch and your safety may be at risk. Depending on where you live, continuing to drive on such thin tread could actually be against the law.

      "Most states require a minimum of 2/32 of an inch (approximately 1.6 mm) of tread, but two require less, some have no requirements, and some defer to the federal criterion for commercial vehicle safety inspections," reports the National Center for Biotechnology Information.

      Why check tire tread depth?

      With adequate tire tread depth, your car is able to grip the road. This is especially important when roads are snowy or wet, or when you’re driving on less-than-ideal surfaces. Once tread becomes shallow, your tires are more prone to slipping and sliding, creating a dangerous situation for yourself and other drivers on the road.

      When your tires are worn, other components of your vehicle can begin to wear prematurely, too, as your vehicle experiences excess strain. While new tires can be a big investment, they’re an investment worth making.

      Check your tire tread depth today!

      Reach into your pocket and pull out your spare change. Give the penny test a try—it only takes a few minutes—and find out if it's the right time to replace your tires. If you're short on change, just find your nearest Firestone Complete Auto Care. Our stores offer free tire inspections that include tire tread depth measurement!

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      How to correctly measure the tread depth of a tire?

      The tread is a very important structural part of the tire, which indirectly and directly affects the safety of your trip. In order to be sure of your rubber, you will have to measure the residual tread depth a couple of times a season.

      In order to determine the exact remaining tread in millimeters, you can use one of several measurement options. The easiest and most affordable option for everyone is to check the tread depth using wear indicators. nine0003

      This method of measuring the remaining tread depth is accurate and simple, and most importantly, in this way any car enthusiast can find out the remaining tread of his tire.

      Tire manufacturers implement several indicator options: numeric and ribs. They have the same meaning and principle.

      (example of wear indicators)

      1) numerical wear indicator

      of a numerical indicator of wear- these are different depths of the number on the tire itself. As the rubber wears, the numbers themselves disappear, showing you the remaining tread depth in millimeters. nine0003

      As a rule, a numerical wear indicator is located on the tire tread. Looking at the tread, you will notice numbers arranged in a row, from 1 to 8. The last number is your tread depth in millimeters.

      2) Rib wear indicator

      The ribs as a wear indicator have the same principle as the numeric one, with one exception, they indicate the critical point in wheel wear at which the tire needs to be replaced to a new one. nine0003

      If your tire wear indicator is on the same level as the tread, then it's time to change the tire.

      (Examples of wear indicators)

      3) Special gauges for measuring tread depth

      If you have some mistrust of wear indicators on the tires themselves, then we hasten to please you. You can measure the tread height of your tire using specialized devices. These devices include the “tread gauge” and “caliper”. nine0003

      These devices are either mechanical or electronic. However, there is no fundamental difference in the measurement algorithm or their accuracy.

      (Electronic Tread Depth Gauge)

      Anyone can measure the tread depth of your wheel with these devices. Below is a brief measurement algorithm.

      The measuring part must be placed on the deepest point of the tread channel and the device will show you the residual part of the projector in millimeters. For a better understanding of the condition of the wheel, you will have to do this procedure in several places on the tire. This is necessary because the tire, in some cases, may wear unevenly. nine0003

      How to evaluate tread wear?

      You have taken the necessary measurements and know the remaining tread depth in millimeters. At what numbers can you drive further, and at what time is it time to change a tire?

      For passenger car tires, a tread depth of 2 mm is considered safe. If your tire's tread depth is less than 2mm, then it's time to change your tires. (The “rib” wear indicator also measures 2 millimeters)

      Please note that these figures are not recommendations. A tire with a tread depth of less than 2 millimeters loses stability on the road due to poor grip and water drainage.

      (Table showing how the grip of a tire with different tread depth changes with increasing speed)

      How to check the tread depth of a tire with a coin?

      If it so happens that you don't have any measuring device at hand, then you should use the wear indicators on the tires themselves. The coin trick is too imprecise a measurement. And wear indicators are present on the tires of any automaker. Measuring the tread depth with a wear indicator is preferable and more accurate than measuring with a coin. nine0003

      From the same kind of myths as measuring the tread with a coin - “How to deepen the tread on a car tire?”. Safe, unfortunately not.

      If your tire already has a wear indicator, then the remaining depth of the rubber coating to the cord is very small. It is impossible to drive safely on such a tire, and if you try to cut the tread, the tire will become unusable.

      Total

      As already mentioned above, monitoring the tread of your tires is an important feature of the safe operation of the car. Checking your tires for residual tread depth doesn't take long, but it can save you from a serious road traction accident. Fortunately, automakers help us monitor the wear process by installing wear indicators on their tires, which makes it much easier to check them for remaining tread depth. If you do not want to control the tread depth of your tires yourself, you can always visit a specialized service station, where mechanics will help you with all measurements. Safe roads for you

      How to determine the remaining tread on a tire?

      Proper vehicle maintenance also includes monitoring the condition of the tread. Gradually, tires wear out, wear out under the influence of constant loads. Branded tires last longer, original tires for mini tractors are made in compliance with the most stringent quality standards. As practice shows, with proper operation, it will last the declared period.

      The average life of tires is 5-7 years. Rubber lasts this long only if it is fully cared for and properly exploited. Often, the owners neglect the elementary rules for care, which greatly reduces the life of the tires. Much depends on the state of the suspension system, as well as on the driving style. Under extreme use, the tread wears out much faster. nine0003

      Measuring with a caliper

      The easiest way to determine how much tread is left is to use a caliper. This tool has a depth gauge, with which you can carry out all studies with an accuracy of tenths of a millimeter. First you need to deal with the scale, the exact data look in the field located below the main values.

      The measurement algorithm is as follows:

      • I wash the tire or place of measurement, with the first option, you can also evaluate wear; nine0126
      • if the rubber is worn unevenly, we work in the place of the greatest abrasion;
      • we place the caliper across the groove and extend the depth gauge until it stops;
      • we fix the scale with a special clamp by turning the wheel on the tool.

      The resulting value indicates the remaining tread depth of the wheel. On the classical scale, we count tenths of a millimeter and add them to the main figure. In this case, the most convenient models with an electronic display. nine0003

      Using a special tool

      There is a specialized tool for checking residual tread - it is used at stations, factories and other facilities. With it, you can accurately calculate the values ​​by determining the height of the rubber. If you plan to often carry out such procedures, it is better to buy your own tool. In other cases, you can visit a service station and use this service.

      The most reliable information can be obtained by measuring several wheels, preferably in 2-3 places. So it will be possible to recognize uneven wear, the cause of which may be incorrect wheel alignment or other suspension failures. nine0003

      Measuring with a ruler

      If you don't have a specialized tool at hand, you can also use this method. But here accuracy suffers and you will get only approximate values, without tenths of a millimeter. This option is suitable for a superficial assessment; when obtaining boundary or lower values, it is worth checking with a tool designed for such tasks.


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