The Washington Quarter Test versus The Lincoln Penny Test. For many years, the Lincoln penny was the tried and true test to know when to replace a worn tire.
That approach has been updated by the “new” Washington quarter test and accepted by many in the tire industry.
Originally, it was mandated that a tire be replaced when it was worn down to 2/32”, a DOT (Department of Transportation) standard for minimum legal tread depth. For those that understand a tire’s construction, this would put the tread depth equal to the “wear bars” in the tread. That unsafe tire’s got to go!
Basically 2/32” of tread depth could be found in a simple test using the Lincoln penny (it’s 2/32” from a penny’s edge to the top of Abe’s head). If could see the top of Lincoln’s head when you inverted a penny (Lincoln’s head upside down), and stuck it down into the tread, then the tire was completely worn out, unsafe and should be replaced.
NOW ~ THE NEW AND IMPROVED TEST ~ Take a quarter instead of a penny. If it is inserted into the lowest worn slot or groove on the tire face and you can see the top of Washington’s head, then the tire should be replaced. This ‘new’ distance (from the top of George’s head to the rim of the quarter) is 4/32” (1/8” vs. a new tire at 10 or more/32”!). At this tread depth, the tire has lost a significant amount of traction, especially when braking on a wet surface, as proven in several industry tests.
In an article from Auto Week, the safety implications of proper tire tread depth was demonstrated by the folks at Tire Rack, an online tire company. They did tests, with an eye-opening video, on the difference between a new tire @ 10/32 of an inch, a worn tire @ 4/32 and a completely worn-out tire @2/32. Check out the video on their website.
Here’s an excerpt from that article:
[In the tests…} The control car stopped at 195.2 feet with new tires in the rain.
The next test used the same car, but the treads were worn to 4/32 of an inch, about the distance between the top of a quarter and Washington’s head. That car took an additional 95 feet to stop on the slick track.
At 2/32 of an inch of tread (the older Lincoln-penny test), the car skidded to a stop at a lengthy 378.8 feet, almost 90 feet more than the Washington-[quarter] tires and 183.6 feet farther than new tires. Maybe more importantly, the last car was still traveling at 44 mph when the Washington-[quarter] test car stopped.
The only thing between you and Mother Earth, regardless of how cool, fast and high-tech your car may be, is the contact patch of 4 tires. Don’t you and your family deserve to be on safe tires? At Pride Auto Care, we understand. See us today for all your tire and automotive service needs.
filed under: Auto News, TiresTags: Tire Repair, tires, wheels
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.
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.
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.
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.
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.
In fact, the average life of any tire is 5-7 years, but a lot depends on how the owner treats his car. Aggressive driving, improper seasonal tire storage, unrepaired suspension/balancing problems, incorrect pressure and other errors can significantly shorten tire life. But worn tires can be a serious problem on the road: an increased risk of uncontrolled skidding, hydroplaning, even accidents is the price that drivers and passengers have to pay for using old tires.
Each manufacturer indicates the so-called wear index on the tire profile, which most often looks like the inscription “Treadwear 100” and means a maximum of 48,000 km on a standard road surface (polygon). In a real environment and often not the most ideal roads, this number actually needs to be divided by 1.5 - we get 36,000 km.
By analogy, if the wear resistance index is 150, then this means “factory” 72 thousand km, 200 - 96 thousand km., and so on.
What are the dangers of worn tires on the road:
adhesion to the roadway deteriorates, which leads to an increased likelihood of skidding, accidents, hydroplaning in case of rainy weather;
reduced cross-country ability in off-road conditions;
increases the risk of a tire puncture while driving.
It is also worth remembering that the issue of tire wear is regulated by traffic rules, and you can get a fine for using “bald” rubber. Knowing what maximum tire wear is acceptable, this is easy to avoid: 1.5-2 mm for summer, and 4-5 mm for winter (a more accurate figure is indicated by the manufacturer).
1. According to the wear indicator on the tire. To find this indicator, you need to inspect the side of the tire and find one of the markings: a triangle, a company logo, a snowflake, or the abbreviation TWI.
If the tread has worn down to this indicator, it means that the tire needs to be disposed of urgently.
2. Many people in the old fashioned way prefer to use a 10-kopeck coin. Insert it into the tread with the inscription "10 kopecks" towards you, and if it is visible, the wear level is too high, you need to replace the tire. This method is convenient, but not entirely accurate: by measuring wear in different parts of the tire in this way, it will be difficult to estimate its unevenness by eye, and this is also an extremely important indicator.
3. It is optimal to use a special gauge, depth ruler or caliper for these purposes. This will allow you to measure the wear of the tread in different parts of the tire with an accuracy of up to a millimeter and understand if there is uneven wear.
If measurements show different results in different parts of the tread, it is important to determine exactly how your tires wear in order to understand where and what the operating error is.
If the tread wears more on the sides and the center wears off less, this means that the tire pressure is insufficient and the contact patch with the road is not correct. This leads not only to poor vehicle stability, but also to increased fuel consumption.
If the tread is worn down the middle but the sidewalls are fine, then your tires are overinflated. Sometimes this is done intentionally in order to save fuel, but in this case, the tires will still have to be changed ahead of schedule.
There is also the possibility of increased wear on the inside or outside of the tread - this indicates an incorrect camber. A visual table with wear options and their causes:
Cracks on the sides of tires can indicate frequent off-road driving, improper storage, low-quality rubber or long service life, as well as incorrect tire pressure.
Bulges or "hernias" on the sides of the tires appear as a result of the side part hitting hard obstacles.
Tires with such damage are not recommended.
Dents on the tread indicate insufficient depreciation and unadjusted camber. Having found such damage, it is necessary to drive the car to the service and make sure that the suspension is in good condition.
Individual wear spots on the tread indicate aggressive driving / braking, skidding with wheel locks, or prolonged parking of the car in one position.
Most often, this is required for the sale and purchase of used tires in order to orient the buyer in the degree of their wear. Many sellers give this figure at random, but this method has nothing to do with the actual assessment of the degree of tire wear. It is also important to understand that a conditional 50% wear for a summer tire is an acceptable value, while 50% wear of a winter tire tread is a sign that the tire cannot be used. Therefore, it is important to know how to accurately determine the percentage of tire wear so as not to get into an unpleasant situation.
Many people divide the actual tread height by the height of the same, but new tire, and get a certain percentage of wear. This would be correct, if not for one BUT: we cannot physically erase the tread to zero, and the law prohibits the use of tires with a tread below the permitted values.
You can calculate actual tire wear by dividing the difference between the new tire height and the actual tire height by the difference between the new tire tread height and the minimum possible tread height for that tire, and then multiplying this number by 100.
If it is impossible to find out the height of the same, but with a new tire, use the average values of your tire type:
| Tire type | Average tread height at start of use |
| Winter tires with Scandinavian tread | 10 mm |
| Winter with regular or asymmetric tread | 9 mm |
| High-speed winter | 7 mm |
| Summer tires with classic tread | 8 mm |
| Summer speed | 7 mm |
You can check summer tires for wear a little less often than winter tires, since in summer the tread depth is not so important for patency.
If you have assessed the condition of your tires on all of the above factors and realized that the tires are worn out, be sure to replace them with new ones as soon as possible.
We have already written how to check the geometry of the body, generator, ignition system, battery, engine, running gear when inspecting a used car. In this article we will tell you how to check the tires when buying a used car.
Some experts say that using used tires is like playing Russian roulette - you only have to rely on luck. And to make the case really happy, you should check the wheels as carefully as possible.
Tires are a guarantee of safety on the road.
When inspecting a car and used tires, check the following:
Each of the parameters is important in its own way, and therefore ignoring at least one of them can significantly reduce the level of safety on the road.
We recommend checking first. If the tires have served their allotted time, further operation does not seem rational. This is easy to do - the date consists of two digits: the week number and year of issue, applied to the outside of the rubber. If, upon inspection of the machine, it is found that the numbers on each wheel are different, then this indicates a non-simultaneous replacement of the wheels. The reason for the replacement, if the service life has not yet come up, you should ask the seller.
A visual inspection is sufficient to check tire wear. It is important that tire wear (if any) is uniform over the entire circumference of the wheel. Uneven tire wear can be a sign of wheel imbalance, and it also indicates a possible sloppy driving style of the previous owner, which can cause several more problems when operating a car. Increased wear on the outside indicates insufficient tire pressure, which should also be checked before a test drive. The operation of such wheels is fraught with the fact that in corners the rubber will not “hold” the road well. If the center part was more subject to wear, get ready for a decrease in acceleration, handling and braking.
When buying a car, be sure to pay attention to this parameter. Tests show that the permissible tread depth should be at least half of the original - for summer tires it is at least 3 mm (1.6 mm by law, but it would be better to leave a margin), for winter tires - at least 4 mm.
It is not difficult to check the depth - in car dealerships you can buy a special probe with marks or use a simple ruler.
When inspecting the tread, it is not superfluous to check for signs of repair from the inside (on a smooth surface). By themselves, the patches on the tread are not critical, but only if their number does not exceed a couple of pieces per wheel, and their size is a third of the width of the pattern. Otherwise, the operation of the "horse" on such wheels should be abandoned. Pay attention to the nature of the patch - the restored tread pattern (the so-called "grooving") can result in a tire rupture.
The tire grips the road surface across the entire tread width. The edges of the tire also have an impact on braking performance. The smaller they become, the less grip the rubber has on the road surface, and therefore the risk of driving on wet or slippery surfaces increases. A worn leading edge indicates problems with the car's suspension, which is also worth paying attention to.
You can check this part of the tread "by touch" - the problem is present if the teeth on the tread edges differ in sharpness.
Tire micro cracks can occur even under conditions of minimal rubber wear and careful storage. The average service life of rubber is 5 years, but, as a rule, by the end of the term, the tire naturally becomes unusable. In the presence of small cracks, it is not recommended to exceed the speed of more than 80 kilometers per hour, otherwise the chances of complete tire wear increase rapidly. Deep cracks appear with a large degree of delamination of the tire. The use of such tires is highly discouraged.
Defects in the form of cuts and repair marks are a clear signal to stay away from the selected used rubber. As a rule, tire side cuts are dangerous due to the fact that the repair of such defects is extremely difficult and not gives a further guarantee of the quality of rubber operation.
But, in addition, it is necessary to check and make sure that there are no hidden damages. Deformation of the tire carcass in the form of dents and creases can be the result of driving or parking on a flat tire, as well as a strong impact. The end of the service life in this case may come earlier than expected.
The internal delamination of the tire is extremely difficult to detect. A warning can be various types of swelling on the inside of the tire. Visible breaks in the layer are also possible. Check the degree of puncture of the tire - when pressed with two thumbs, the tire should not deform much, but will quickly return to its original shape.
These tire and wheel test parameters apply to both summer and winter tires. But, in the cold season, when the car is "changed" in winter tires, some other factors should be taken into account.
In winter, buying a car with winter tires is considered correct, but another situation is possible, so do not neglect to inspect the wheels.
First of all, you should check what the car is “shod” in - it can be idle for a long time, especially if the transaction takes place in the car market. Winter wheels are divided into two types: studded and friction.
Equally important is the tread depth. For 100%, it is customary to take the tread depth of new tires, 0% - unusable, respectively. The minimum permitted tread depth for winter tires is 4 mm, otherwise 0%. From the factory, tires are produced with different depths. Keep in mind that if the initial depth reached 8 mm, then 4 mm is not 50% wear, as some sellers say.
A buyer's vigilance will be a guarantee of a good deal. Bad tires in the general good condition of the car is not always a reason to refuse a purchase. If the wear is natural and even, and also corresponds to the average life of tires, the option of purchasing a car is worth considering. You can always eventually replace the rubber with one that will inspire confidence.
In order to avoid doubts about the history of the purchased car during the inspection, check the history of the car using the Autocode online service. To obtain a complete report, only the VIN, chassis number or state number of the vehicle of interest is required.
By driving in unique car numbers, you will receive the following data:
If you are a professional car dealer, you can also use the Autocode Profi service of unlimited car checks. Autocode Profi allows you to quickly check a large number of cars, add comments to reports, create your own lists of liquid vehicles, quickly compare options and store vehicle data in an orderly manner.
Tire wear or other negative factors may be hidden by the seller. So that they do not subsequently lead to problems in other parts of the machine, order an on-site Autocode check. The specialist will arrive at the place at any time and conduct a professional inspection of the vehicle. Checking the machine through Autocode will help to verify the correctness of your assumptions or refute them.
If there are no serious problems in the history and technical part of the car and you decide to buy, take the final step - enter the seller's passport data through the car owner verification service. This service will show whether he has problems with the law, whether his passport is valid, whether there are debts and enforcement proceedings.
