How to measure tire tread depth with a coin


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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      safe tread height, traffic rules requirements


      The tire tread is the outer part of the wheel that provides traction in all weather conditions. The protectors inevitably wear out during the operation of the car, the working height of the slope decreases. The residual tread depth should be periodically monitored and the set of tires should be renewed in time - this will reduce the risk of losing control of the car and save the car owner from fines from the traffic police.

      nine0005 Tread wear rate depends on many factors:

      Measuring the thickness of the tread layer will allow you to accurately determine the degree of tire wear and make a decision in time to replace them with new ones.


      Different tires have different wear limits. Tread depth affects vehicle handling and road safety.

      According to Chapter 5 of the SDA, limiting norms for the height of the tread pattern have been established. For category M1 - passenger cars - as well as vehicles of categories N1, O1 and O2, the minimum allowable value is 1.6 mm. When using winter tires on snowy or icy surfaces - the limit is 4 mm. nine0006

      Let us explain what categories of vehicles we are talking about:

      • N1 - vehicles intended for the carriage of goods, having a technically permissible maximum mass of not more than 3.5 tons;

      • O1 - trailers, the technically permissible maximum mass of which is not more than 0.75 tons;

      • O2 - trailers, the technically permissible maximum weight of which is over 0.75 tons, but not more than 3. 5 tons. nine0006

      The traffic police officer has the right to measure the residual depth with a verified device. In case of a recorded violation, a fine is imposed on the car owner.



      The new summer tire has an average tread depth of 7-8 mm. The service life of summer tires is usually 3-5 seasons with average mileage and moderate driving style.

      Residual height limitation by law is 1.6 mm. However, with a remaining outer layer of 3 mm, the machine is already difficult to control, grip deteriorates, and a safety hazard arises. nine0006

      Do not wait until the critical value is reached. Make sure you change tires in advance.

      Winter tires are used in severe weather conditions: low temperatures, icy conditions, on snowy road surfaces. Worn elements make the tire ineffective on slippery winter roads. Accordingly, a more serious approach to the condition of the tire tread is needed.

      Non-studded friction tire (velcro) with tread depth 8-9mm. A new studded model - from 9 to 11 mm, some firms produce a tread with a height of 12-18 mm.

      If the tread wear is up to 4-5 mm, the winter set of tires needs to be replaced. In addition, the loss of more than 50% of the metal spikes is also a reason to change the car's shoes.

      The average life of winter tires is 2-4 years.



      Universal all-weather is used in a temperate climate both in winter and in summer, it is optimal at temperatures from +10 to -10˚C. This type of tire is not suitable for use in snowfall or severe frosts. SDA allows the use of all-season tires in the winter if there is a special marking:

      All-season tires last 3-4 years on average. In summer, at high temperatures, all-weather tires wear out much faster. It is recommended to buy new tires when the tread layer is abraded to a value of 2-2.5 mm.


      You can estimate the remaining tread layer in various ways:

      1. On some tire models there are special volumetric indicators in the form of jumpers. Check: if the tread layer is worn down to the level of the jumpers, the tire is not suitable for further use. nine0006

      2. On the surface of certain types of tires, manufacturers knock out numbers of various depths. Depreciation is assessed visually - by the visibility of individual numbers.

      3. With the help of measuring instruments: from a metal ruler, caliper, depth gauge to an electronic tread depth gauge.

      Many motorists measure the remaining tread depth with a coin. Warning: this method of measurement is not accurate. It will not show you actual tire wear figures. nine0006

      Tire tread height should be measured at least at 6 different points, preferably at 9 or even 12: in the center and from both edges of the tread, at different points around the circumference of the tire. The measurement results at all specified points must match. If they do not match, then the tire wears unevenly. The driver should find out why this is happening. Some causes of uneven tire wear are low or high pressure in them relative to the regular one, suspension failure, extreme driving style. nine0006

      Old tires have become unusable, the amount of tread remaining is approaching a critical line - no need to take risks, it's time to change your car's shoes. There is a great temptation to get by with small financial costs and purchase a set of used tires. Be careful!

      Sellers advertise used tires as good or excellent condition. Do not be too lazy to personally measure the height of the tread layer. And remember: for winter tires, a residual tread depth of 4 mm is already 100% wear. nine0006

      When buying used tires with tires, it is important to remember that tires from different manufacturers and seasons initially have different tread heights (when they are new). And most importantly: the tires have, accordingly, different wear limits - the tread depth at which the tire begins to lose important characteristics. These differences are most noticeable in winter and summer tires. Keep these points in mind when measuring the remaining tread depth of used tires.

      The quality of domestic roads, unfortunately, does not allow tires to be used for 7–10 years. If you still decide to buy a used kit, check the year of manufacture - it is better not to consider tires older than 8 years. nine0006

      • there is no guarantee for tires bought from hands;


      • the seller can cheat - for example, offer tires from different manufacturers in one set. Some especially enterprising salesmen even cut the tread on the worn rubber, as if the tires had not yet worn out;


      • you will have to spend a lot of time picking up tires from private sellers - much of what is put up for sale is only suitable for recycling; nine0006


      • Products may have hidden or visible defects. Visible are punctures, tears, cuts. A tire with a lot of damage can collapse in motion. Hidden defects include damage to the cord, which most often occurs after punctures or a strong blow. A car with such a malfunction may wiggle on the road, and it will be unstable;


      • the goods were stored in the wrong conditions, for example, under direct sunlight - this reduces the life of the tires and they will quickly become unusable, even if the residual tread depth is ideal; nine0006


      • it is not always possible to carry out a tire fitting in the presence of the seller, you will have to check the kit yourself after payment.


      Without a specialist, there is a risk of buying tires that you cannot use. Don't skimp on safety. Purchasing a new set of tires will require more investment, but will pay off with a long period of trouble-free operation.


      • The maximum permissible residual tread depth for a passenger car is 1.6 mm in summer and 4 mm in winter. nine0006


      • SDA strictly regulate the residual height of the tread pattern. Violation of traffic rules is a reason for drawing up an administrative protocol.


      • For your own safety, replace worn tires on time. Better for new ones.



      How to check tread wear

      Statistics say that a third of car drivers do not know how to determine the degree of tire wear and the need to replace them. Also, not all car drivers know what is the minimum tread depth allowed by our legislation. nine0006

      Latvian legislation stipulates that the minimum allowable tread depth for summer tires is 1.6 mm , and, in turn, for 3 winter tires - 4 mm. Compared to other European countries, Latvia leads in this requirement, because in other regions of Europe, the requirements require a minimum tread depth of 3 mm. It should be emphasized that usually the tread depth of new tires is 6-8 mm for summer tires and 8-10 mm for winter tires. nine0006

      Many factors contribute to tire wear, one of which is driving style . For fans of aggressive driving, tires wear out faster because they warm up faster and begin to wear out. In addition, incorrect tire pressure , too much weight load and running gear defects contribute to tire wear. Therefore, it is necessary to regularly check the condition of the tires, because from the point of view of safety and handling, they are the most important part of the car. nine0006

      Every driver should carry out a visual inspection of tires at least once a month, since each tire has wear indicators, most often located in the water channels. First of all, it is necessary to assess the degree of wear of the tread. This can be done in several ways, such as using a digital tread gauge.

      New tire 9 Used tire

      195

      But the easiest way to tell if a tire has reached the minimum mark is to check the tread depth with a two-lat coin.


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