Tires are one of the most commonly replaced items on your vehicle as they endure thousands of miles of high-speed revolutions on hard pavement. As they shed their tread due to everyday use, they become less effective bit by bit.
Knowing how to measure tire tread will help you determine when it’s the right time to replace your tires. Without this basic understanding, you risk changing them too late and putting your safety at risk or changing them too early and wasting money.
Below, we'll cover how to measure tire tread and other tire-read-related topics to help you stay safe, save money, and know what to look out for when tire shopping.
Understanding the Sections of Tire TreadBefore you can correctly learn how to measure tire tread, you must first know the main sections of the tread. Your tire's tread has three main sections: the outer shoulder, contact patch, and inner shoulder. Spanning the tire's circumference are deep grooves — called channels — that separate the tread.
The outer shoulder is the outermost section of the tire and is outside of the last channel. On the opposite edge of the outer shoulder is the inner shoulder.
The contact patch is the area between the two shoulders — it’s the tire's main contact point with the road. This is the area where the tread blocks are thickest and where you measure the tire tread depth.
How to Measure Tire TreadDetermining a tire’s tread depth involves measuring from the lowest point in the channel to the top of the tread on the contact patch.
This depth is important because the channels are responsible for shuttling water and slush away from the contact patch to maximize traction. If the tread isn’t deep enough, the channels will be too shallow to move water and slush effectively, reducing traction and increasing the risk of hydroplaning on wet roads.
There are three main relatively simple ways to measure tread depth, but some are more precise than others.
If you look closely at the tire's channels, you'll notice small, raised bars that span the channels. These are tread wear indicator bars. If the tire tread wears to the point that it's even with the wear bars, your tires need replacing.
Use a QuarterA simple way to check tread depth is using the nickel or quarter test. Hold a quarter or nickel between your thumb and forefinger and place the coin inside the channel, with the top of the figurehead’s head facing the tire. If any portion of the tread is covering the figurehead, you have a safe amount of tread remaining on the tire. If the full figurehead is exposed, it's time for new tires.
Always check your tires in several places as they don't always wear evenly and could be low in some areas.
Use a Tire Tread Depth GaugeThe most official and accurate way to check tire tread is with a tire tread depth gauge.
The tread depth gauge will have a blade side that looks similar to a flat-head screwdriver and a gauge side with either a manual gauge with measurement marks on it or a digital readout. You can pick one up at any auto parts store for about $5 (manual) or $15 (digital).
Fully extend the blade side and place the blade into a channel between two tread blocks on the contact patch. Slide the gauge toward the tread until the gauge's flanges rest on the tread blocks on the contact patch. Read the measurement on the gauge.
Repeat the measurement on several parts of the contact patch to ensure there are no low spots.
Using a gauge will give you the most accurate results and will allow you to compare your tire's tread depth to the requirements in your province.
Tread Depth RequirementsCanadian law requires a minimum 1.6 mm tread depth, but some provinces have even stricter requirements. The province-specific tread depth rules are as follows:
32 cm above the tread wear indicator bars and no baldness on the adjacent tread 
6 mmWhile the legal minimums are great, tire experts often note they aren't always the safest recommendations.
Large portions of Canada set the legal minimum tread depth at 1.6 mm. Tire Rack experts tested this minimum against 3.175 mm of tread. They found a vehicle with tires that had 1.6 mm of tread took an extra 30.5 metres to stop from 112 km/h than the same vehicle equipped with tires that had 3.175 mm of tread.
For this reason, Tire Rack and many other automotive experts recommend new tires when your existing tires reach 3.175 mm of tread. Additionally, they recommend swapping out those snow tires at 3.96 mm.
How to Find the Best-Wearing Tire for Your BudgetMany variables come into play when shopping for a tire, but much of the research is already complete if you know what to look for.
Some shoppers simply follow the lead of the tire salesperson or mechanic who generally wants to sell the most expensive tire they can. Without a full understanding of how tires work, it’s easy to assume the priciest tire will last the longest. But this is't always the case.
A lot more goes into tire pricing than longevity. There are also special compounds that make the tire quieter, puncture resistant, or more stable in corners and braking.
If your main interest is a long-lasting tire, don't fall for a tire salesperson directing you to the higher-priced tires. Instead, focus on the Uniform Tire Quality Grade (UTQG) stamped on the sidewall. The UTQG will be a three-digit code followed by two letters.
The three digits are the treadwear rating, and the two letters are the traction and temperature rating. The higher the three-digit number, the longer the manufacturer expects the tire tread to last.
There are no exact numbers the three-digit code translates to, but understanding its meaning is simple.
When determining a tire's treadwear rating, the base control tire has a 100 rating. The tire manufacturer estimates a 200 treadwear tire will last twice as long as that control tire, a 400 will last four times as long, and so on.
So, you may see a premium $150 tire may have only a 300 treadwear rating but lots of other attractive features that drive up the price. However, there could also be a $70 tire next to it with fewer features but a 700 treadwear rating. If your focus is longevity, it's clear which is the right tire for you — although that $150 tire likely has benefits the $70 doesn’t.
Manufacturers estimate the treadwear rating by driving 11,520 km on a 640-km track. They stop every 1,280 km to check the remaining tread. They then use these measurements to the projected treadwear ratings.
How to Maximize Tire LifeBarring manufacturer defects, tires will last as long as they're supposed to, given your vehicle is in good mechanical condition and properly maintained.
However, there are steps you can take to maximize the life of your tires.
Tire pressure is the first rule for maximizing tire life. Check the air pressure in your tires weekly — or every time you refuel — and compare it to the pressure requirements on the tire placard in your door frame.
The recommended pressure will generally fall somewhere between 32 and 38 PSI. Too much air pressure can cause the center of the tire to bulge, leading to excessive wear in the middle of the tire. Too little air can cause the center to collapse, putting most of the car's weight on the outer edges, leading to excessive inner and outer wear.
As an added benefit, the correct tire pressure in a vehicle also helps with fuel economy.
Never fill your tires to the maximum PSI listed on the tire unless this is the pressure listed on the tire placard.
Adjust to the Driving ConditionsSlippery driving conditions, like rain- or snow-slicked streets can lead to wheel-slip, which creates excess heat and wears out tires quickly.
Always adjust your driving style to road conditions. You’ll avoid spinning the tires and prolong their life.
Tires rarely sit perpendicular to the road. Most manufacturers engineer the suspension system so the tires sit at a slight inward angle. This angle allows the tire and suspension to flex outward as you go around corners, so more of the tire's contact patch touches the road.
This means as you're driving straight, most of the car's weight rides on the inner portion of the tire. Rotating the tires in the manufacturer's specified intervals puts the tire in a different position on the vehicle, slightly changing its angle to prevent uneven tire wear.
Over time, all the flexing in the suspension and bumps in the road can throw off the angles. When a mechanic performs an alignment, they reset the angles so the tires are in the position the manufacturer recommends, ensuring they wear evenly.
Quality Vehicles With Quality Tires at ClutchTires are far and away one of the most critical parts of automotive safety, so it’s important to make sure you maintain them properly.
This maintenance goes beyond just rotating them and keeping the pressure within specifications. You must also monitor your tread depth to ensure there is enough to provide you with the traction you need.
Fortunately, there are several ways to measure tire tread, and some require no tools at all. All you need is good vision and maybe a coin. However, if you want to be 100% certain you’re legal and safe, shelling out $5-$15 for a tread depth gauge will help.
All our preowned vehicles at Clutch have been through a 210-point inspection, including the tires. Any tires that have less than 4mm of tread depth are replaced with quality new tires, giving you peace of mind.
Plus, all vehicles purchased online come with a 10-day no-risk guarantee that allows you to return the vehicle for a full refund within 10 days of receiving it. Beyond that, all Clutch vehicles come with a 90-day or 6,000 km limited warranty.
Finally, our car-buying experience is 100% online and free from any high-pressure sales tactics of most used car dealerships.
Check out our range of available vehicles and shop from the convenience of your home.
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PreviousTires are a huge expense for any vehicle and proper maintenance ensures you’re always driving on the safest set. Check out our comprehensive tire maintenance guide. It'll help you get the best life out of your tires, and the best bang for your auto buck.
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Read this Story Every car owner knows that driving on "bald" tires is dangerous. Therefore, the questions of how to "catch" the moment when you need to replace tires, how to calculate wear and how the tire wear indicator helps in this, always remain relevant. In order to find out the degree of wear, various digital meters, a ruler, and a caliper are often used to measure the tread depth.
You can also use any object: a match, a coin, a strip of metal. It is enough just to insert them into the tread and make marks, which in the future will allow you to receive current information about wear. You can calculate wear as a percentage using a special formula. But the most convenient and accurate way to get information about wear are tire wear indicators, which are installed by manufacturers. nine0005
Where is the wear indicator?
It must be understood that in Europe and the Russian Federation there are uniform maximum allowable tread heights. For summer tires they are 1.6 mm, and for winter tires - from 4 to 6 mm. Then it becomes obvious that we are talking about the tread block. To determine the place where the tire wear indicator is located, you should find a special mark on its side surface, which can be in the form of the TWI abbreviation, the manufacturer's logo, a small triangle or bibendum for Michelin tires.
An example is the Michelin rubber wear indicator located in the center groove of the tread. Its location is indicated by a small bibendum - a rubber man, the Michelin symbol. nine0005
Many manufacturers install intermediate wear indicators in the treads, the disappearance of which indicates critical wear and the need for replacement.
An example of such an indicator on the Continental
Bridgestone Tires, unlike other manufacturers of this brand, have not one, but two types of indicators. First of all, these are indicators of complete wear, having the form of small arrows that appear, when the tread height reaches 1.6mm. Indicators of this type are located in six places and if they appear, the tire needs to be replaced. In addition, there is a Bridgestone winter tire wear indicator showing 55% wear . It has the form of ribbed lugs in the tread, which are installed in four places. Nokian 
If at least one of them appears during operation, then this indicates that the rubber can no longer be used as winter tires. The photo below shows what they look like. nine0004
Tires. These tires can often see digital 9,0003 Nokian tire tire wear in the form of digits , which have different depths and were squeezed out to a different depth of different depths . This indicator, which shows the degree of change in tread height in millimeters, is called DSI - Driving Safety Indicator. As the tire wears out, the numbers fade from higher to lower and when the minimum level of permitted use is reached, they indicate that the tire must be replaced. nine0003 This is clearly seen in the photo of the Nokian Hakkapeliitta 5 tire wear indicator (photo below).
The snowflake, which can be seen in the photo, is an indicator that the tire can be used in winter. In addition, recently on the tires of this manufacturer, next to the numbers and the snowflake, you can see the image of a drop, the disappearance of which means an increased risk of aquaplaning.
You should know that digital indicators are also in the form of numbers indicating the percentage of the ratio of the worn tread height to the original one, as well as in the form of one segmented number, each segment of which is pressed to a different depth. nine0005
Of course, you can measure using a special formula for calculating wear, which looks like this:
check their status.
Tire tread can affect the safety and performance of your vehicle while driving. While you may not think about your tire tread every time you drive, it's important to check to make sure your tires are in good working order from time to time. Ready to talk about tire tread depth? Let's dive in. nine0005
Tire tread depth is the vertical measurement between the top of the tread and the lowest groove. In the US, tire tread depth is measured in 32 inches. When tires are new, they have a tread depth of 10/32 to 11/32.
In the United States, tires are required by law to have easily recognizable tread wear indicators. As the tire tread wears out, it will eventually line up with the tread wear indicator. At this point, the tire should be replaced. There is too little tread left to provide traction. If the safety wasn't convincing enough, be aware that driving a car with bald tires is also illegal. nine0005
Minimum tolerance is 2/32 inch. This does not mean that tires are absolutely safe if they have 3/32 of the tread left. This is simply the limit at which you will not pass the state safety inspection. As the tread wears out, your tires become less and less safe.
When it comes to safety, your tires are literally where the rubber meets the road. Sufficient tread depth is essential for safe cornering and braking. nine0005
Low tire tread depth can spell disaster for your driving, including:
If you live in an area where it rains or snows frequently, consider changing your tires when they reach 4/32 inches. With worn tires, there is a risk of hydroplaning on wet roads. This is when the tire is unable to direct water through the grooves. The car rides on the surface of the water, and does not touch the asphalt. Thus, the tires cannot respond to the steering system. If you've experienced this, you know how scary it can be. In icy or snowy conditions, the shallow tread depth makes it difficult to stop. You can also fish with your tail when accelerating, or sliding to the side when turning. nine0005
There are also special requirements for driving in hot weather. If you are approaching summer and your tires are nearing the end of their life, keep in mind that hot roads wear them out faster.
Very simple. All you need to check tire tread depth is a penny. Insert a penny with Abraham Lincoln's head upside down. If Abe's top is visible, it's time for new tires. Tamara shows you how to do it in this video. nine0005
Be careful when measuring tread depth. Insert a coin in several places around the tire. Uneven tread wear is not uncommon. Measuring in multiple locations compensates for this.
Correct tire pressure is also critical. Tire pressure is expressed as a number followed by PSI. This means pounds per square inch. 28 PSI means 28 psi. This is a measurement of the force inside the tire applied to one square inch. You can check the recommended tire pressure for your vehicle in your owner's manual or on a sticker inside the driver's side door. For most vehicles, this is around 32 psi. nine0005
If the pressure is too low, the tires wear faster. You will also get leaner gas mileage. This is because it is more difficult for your engine to propel the vehicle on soft tires. Low air pressure also results in a harsh ride.
If you find that your tires are too low, fill them up to the correct pressure. Don't think "the more the better". There are also problems with excessive inflation. When there is too much air in a tire, it has less contact area with the road surface. This complicates processing. It also increases the risk of a blowout. At high speeds, the blowout can be fatal. nine0005
Since the early 1970s, the National Highway Traffic Safety Administration (NHTSA) and international colleagues have been concerned about the dangers of low atmospheric pressure. They were looking for technology that could alert drivers. Evidence was emerging that under-inflated tires were responsible for thousands of car accidents every year. At the end of the decade, NHTSA was also motivated by the energy crisis. Tire pressure affects fuel economy. nine0005
Tire pressure measurement technology became available in the 1980s and was first used by Porsche on a 1987 959 Porsche.
There are two types of TPMS: indirect and direct. Direct pressure sensors are located on the tire stems. If the sensor detects a significant drop in pressure, it sends a warning to the engine computer. The indirect type uses an anti-lock braking system to detect low pressure by measuring wheel speed. Tires rotate at different speeds depending on air pressure. The indirect method is less reliable and has largely been discontinued by manufacturers. nine0005
At Chapel Hill Tire, we've been providing professional automotive services to North Carolina drivers since 1953.
