How to measure your tire size


How to Read & Determine Tire Size for Your Vehicle

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How To Determine Tire Size

Once you have determined it’s time to buy tires, you’ll need to know what size tires are correct for your vehicle. Depending on what you drive, you may be interested in how to find the right tire for your…  

  • Sedans or CUV
  • Light Trucks or SUV
  • Motorcycle
  • RV

This information is usually inside your car’s doorjamb, in your owner’s manual. To ensure your current tire or a replacement tire you may be looking at matches your vehicle’s requirements, it will be good for you to understand how tire sizing works. You may have never paid attention to the string of numbers and letters on every tire, but it’s a gold mine of information.

If you’re unsure of how to read tire measurements from your tire walls, the information and graphics below will tell you how to read tire size, understand and interpret it. If you decide you want to substitute a new size or tire type, consult an authorized tire retailer who can expertly advise you, because many optional tire sizes may have different load capacities and could require wheels of a different rim width or diameter and different inflation pressure.

Not sure you need new tires? Our Tire Replacement Guidance article will help you determine whether it’s time to retire your tires.

Metric Sizing

Most passenger cars, SUVs and light pickups (1/2 ton and smaller) will come with tires that are either P-Metric or Euro-Metric. For P-Metric tires, you’ll see the letter “P” before the number sequence begins: P225/70R16 97H. P-metric is a designation standardized by the Tire and Rim Association for a “passenger car” tire type. For Euro-Metric there will be no preceding letter before the number sequence begins: 225/70R16 98H. Euro-Metric is a designation standardized by the European Tyre and Rim Technical Organization for a “passenger car” tire type.  Both P-Metric and Euro-Metric size tires are designed to primarily be used on passenger vehicles, which can include cars, minivans, SUVs, and other light duty pickup trucks.

If your vehicle is an SUV, Pickup truck or van, you might see a different type of size designation on your placard that is specific for heavy duty light trucks and vans, especially common on ¾ ton and larger pickup trucks and vans. There are two common size types in this category, LT-Metric and Euro-Metric Commercial (aka C-type). Both size types are metric and so use the same structure as P-Metric and Euro-Metric but have some different characters in the size that differentiate them from their passenger car cousins. LT-Metric tires will have the letters “LT” before the size number sequence: LT245/75R17 119/116R Load Range E. Notice that there are two load index numbers and a Load Range, see the section on Load Index for more info.  LT-Metric is a designation standardized by the Tire and Rim Association for a “light truck” type tire. Euro-Metric Commercial or C-Type tires will look very similar to a passenger Euro-Metric size except that there will be a “C” right after the rim size: 23/65R16C 121/119R. Notice that the C-type tires also have two load index numbers. Euro-Metric Commercial, or C-Type is a designation standardized by the European Tyre and Rim Technical Organization for a light truck type tire. Light truck tires are designed to be used on vehicles capable of carrying heavy cargo and are usually only specified by a vehicle manufacturer on vehicles exceeding a certain load capacity.

Other types of tires that fall into the Metric sizing type are Temporary Spares, they start with “T”. If you see a size that starts with “ST,” that means “special trailer” and is only for use on a trailer.

Regardless of whether you are looking at a P-Metric, Euro-Metric, LT-Metric, Euro-Metric Commercial, T or ST tire the numbers in the size mean the same thing.

Width

The first number to appear in your tire size information is the width, in millimeters, of the correct tires for your vehicle: P225/70R16 91S.

Tire width always refers to the measurement from one sidewall to another. Thus, a tire with the measurement “P225” is for a passenger vehicle and has a nominal width of 225 millimeters.

Aspect Ratio

After the slash mark, the next number you see is for the tire’s aspect ratio, which essentially tells you how tall your tire’s profile is: P225/70R16 91S. Aspect ratios are delivered in percentages. Tire makers calculate the aspect ratio by dividing a tire’s height off the rim by its width. If a tire has an aspect ratio of 70, it means the tire’s height is 70% of its width.

Lower aspect ratio tires, such as a 60 series, generally offer vehicle handling performance advantages over higher aspect ratio tires, such as a 75 series, but a typical trade off can be ride harshness.

Construction

After the aspect ratio comes a letter that indicates the type of internal construction maintaining your tire’s stability: P225/70R16 91S.

There are two types of construction that you may see on the sidewall of a tire:

  • R – Radial
  • D or “B” or “-“ – Diagonal or Bias Ply

Radial tires are the most common tires on the road in the United States today; thus “R” will usually be shown in the tire size designation. Radial construction means the tire’s internal ply cords are oriented in a radial direction, from one bead over to the other, essentially perpendicular to the direction of rotation. You may also occasionally see RF indicating a run flat tire or ZR indicating a tire that is a speed rating higher than V.

Rim Diameter

The next number is the diameter code, in inches, of the rim onto which the tire can be mounted. For example, a tire with the P225/70R16 91S would fit a rim with a 16-inch diameter.

Load Index

Load index can be a confusing subject because there are so many different caveats, but we will try to explain everything here.

The next figure after the rim size in the sequence is your tire’s load index, which tells us how much weight, in pounds, the tire can support when fully inflated: P225/70R16 91S

We call it the load “index” because the number doesn’t tell us the precise number of pounds the tire can carry, at least not by itself. However, the number does correspond to a specific load capacity listed in an index. Beginning with 1 and ending with 150, numbers in the load index represent carrying capacities of 99 to 7385 lbs.

There are two types of load types for passenger tires though, Standard Load and Extra Load. If a tire is Standard Load there will be no markings indicating it but if it is Extra Load the letters XL will appear after the size and load index.

Standard Load Euro-Metric: 215/55R17 94V

Extra Load Euro-Metric: 215/55R17 98V XL

Passenger car tires like P-Metric and Euro-Metric will only have one load index number where LT-Metric and Euro-Metric Commercial (C-Type) will have two numbers separated by a slash. The first number is the load index if the tire is used in a single application, the second number is the load index if the tire is used in a dual application. Passenger type tires cannot be used in a dual application. Light truck tires will also have a Load Range that is indicated by a letter, such as Load Range E. Load Range is an older term that is still commonly used in the industry so you may hear your tire dealer reference it but the load index numbers are the best way to ensure you have the proper tire.

One important but often misunderstood facet about load index is that the load index numbers between standards organizations (P-Metric vs Euro-Metric) are not necessarily on the same scale. Meaning that two tires in the two different systems that have the same load index number could have different maximum load capacities. This is why it’s important to not only look at the load index number but also verify the actual load capacity.

Speed Rating

The final figure in a tire size sequence is the speed rating, which is indicated by a letter: P225/70R16 91S. Just as your load index number corresponds to a specific load, your speed rating letter corresponds to a particular speed capability based on a standardized laboratory test.

For example, a tire with speed rating “S” is rated for up to 112 mph, while a tire rated “R” is up to 106 mph. Remember that this isn’t a recommended cruising speed. Of course, you should always follow legal speed limits on roadways.

Replacement tires must have the same or higher speed rating as the vehicle’s Original Equipment to maintain vehicle speed capability. If a vehicle has tires with different speed ratings, it is the speed rating of the “slowest” tire that dictates the vehicle top speed.

Flotation Sizing

There is one last sizing type that you should know about, especially if you are in the market for off road tires for a light truck or SUV. It’s called a Flotation size and the numbers in this sizing format are very different from the Metric formats. Flotation sized tires are similar to LT-Metric tires in application except for a few important points. Number one, they cannot be used in dual applications and number two, an equivalent size tire may have different load capacity than its LT-Metric counterpart.

Overall Diameter

The first number in the Flotation tire size is the overall diameter in inches. Pretty straight forward.

Section Width

The second number is the section width (sidewall to sidewall) measurement in inches. Again, fairly simple.

Construction

After the section width comes a letter that indicates the type of internal construction: 33X12.50R17LT 120Q.

This is the same as is found in the metric sizing systems.

There are two types of construction that you may see on the sidewall of a tire:

  • R – Radial
  • D or “B” or “-“ – Diagonal or Bias Ply

Radial tires are the most common tires on the road in the United States today; thus “R” will usually be shown in the tire size designation. Radial construction means the tire’s internal ply cords are oriented in a radial direction, from one bead over to the other, essentially perpendicular to the direction of rotation.

Rim Diameter

The next number is the diameter code, in inches, of the rim onto which the tire can be mounted. For example, a tire with the 33X12.50R17LT 120Q would fit a rim with a 17-inch diameter.

LT type

The letters LT will be after the Rim Diameter indicating that this tire type is intended for Light Truck vehicles similar to the LT-Metric and Euro-Metric Commercial (C-Type) tires.

Load Index and Speed Rating

Load Index and Speed Rating have the same meaning and format as the tires using the metric sizing system. Note that since flotation tires cannot be used in a dual application there will be only one load index number instead of two.  

Uniform Tire Quality Grading

Another group of stamping on certain types of tires is the Uniform Tire Quality Grading or UTQG. This grading and stamping is required for passenger car tires (i.e. P-metric and Euro-metric) in the all season and summer categories. Dedicated winter tires, Light Truck (LT-Metric, Euro-Metric Commercial, Flotation) and Motorcycle tires are excluded from this requirement.

Quality grading is designed to make the tire purchase decision easier for you. Ideally, the system is intended to provide simple, comparative data so you can make an intelligent buying decision. However, the ratings are based upon test results achieved under special conditions. This means it’s possible to misinterpret the comparative data as it relates to your individual driving habits, conditions, etc. You should still rely on your service or tire professional for assistance. 

Quality grading designates the comparative performance levels of a tire based on government-specified tests but commissioned by the individual tire manufacturers. All tire manufacturers are required to grade regular and all-season passenger tires in three categories:

UTQG

  1. Treadwear
  2. Traction 
  3. Temperature

Treadwear
The treadwear grade is a comparative rating based on the wear rate of the tire when tested under controlled conditions on a specified government test course for 6,000 miles (9,600 km). For example, a tire graded 150 would wear one and a half times as well on the government course as a tire graded 100. However actual tire performance depends on driving habits, road characteristics, service practices, and other factors that can influence the outcome. 

Traction Grades AA, A, B and C 
The traction grades from highest to lowest are AA (the highest), A, B and C. They represent how well tires stop on wet pavement as measured under controlled conditions on specified government test surfaces of asphalt and concrete. C-rated tires will have the lowest traction performance.  

WARNING: THE TRACTION GRADE ASSIGNED IS BASED ON A WET BRAKING (STRAIGHT AHEAD) TRACTION TEST AND DOES NOT INCLUDE CORNERING (TURNING) TRACTION.

Temperature Grades A, B and C 
The temperature grades A, B, and C represent the tire's resistance to the generation of heat and its ability to dissipate heat when tested under controlled conditions on a specified indoor laboratory test wheel. Sustained high temperature can cause the tire’s material to degenerate and reduce tire life, and excessive temperature can lead to sudden tire failure. The grade C corresponds to a performance level all passenger car tires must meet under the Federal Motor Vehicle Safety Standard No. 109. Grades A and B represent higher levels of performance on the laboratory test wheel than the minimum required by law. 

WARNING: THE TEMPERATURE GRADE IS ESTABLISHED FOR A TIRE THAT IS PROPERLY INFLATED AND NOT OVERLOADED. EXCESSIVE SPEED, UNDER INFLATION, OR EXCESSIVE LOADING, EITHER SEPARATELY OR IN COMBINATION, CAN CAUSE HEAT BUILDUP AND POSSIBLE TIRE FAILURE.

DOT Quality Grades 
All passenger car tires must conform to other federal requirements in addition to these grades.

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Tire Replacement Guide - When & How to Replace Tires

Home > Company > Tire Safety > Choosing Tires > Replacement Guidance

Check For Tread Depth

The best way to know if it’s time to buy new tires for your vehicle is to have them inspected by a professional, but there are ways to check them yourself. To meet legal safety standards in the U.S., a tire’s tread needs to be at least 2/32” deep. If the tires do not meet the 2/32” standard or are approaching not meeting it, you should replace your tires. When replacing tires, it’s important to select the right tire size for your vehicle. Not sure what size you need? Learn more about determining tire size.

Tires should also be free of sidewall damage and irregular wear for optimal performance and safety. It’s also a good idea to learn what types of damage can be repaired vs. replaced so that you can safely extend the life of your tires.

You can evaluate your tires on your own through a visual inspection. Start with the tread — the part of the tire that contacts the road surface. Make sure the tire tread is deep enough and worn evenly all the way around without any irregularities. All DOT-regulated tires feature built-in treadwear indicators, commonly called “wear bars”, that will help you see when the tread is getting low. These indicators can be found in various places throughout the tread and will be even with the tread surface when the tread is worn to two-thirty seconds (2/32) of an inch. You should also examine each tire’s sidewall to ensure there is no visible damage.

The Penny Test

You can also use the Penny Test to check your tire tread. This test can be performed in your own driveway in just a few minutes. 

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

  1. Place a penny in the tread of your tire.
  2. Turn the penny so that Lincoln’s head points down into the tread.
  3. See if the top of Lincoln’s head “disappears.” If it does, your tread is still above 2/32” and you're good to go. If you can see his entire head, it may be time to replace the tire because your tread is no longer deep enough.

Check all four tires, especially in areas that look the most worn. If any parts of your tire fail the penny test, it may be time to replace the tire.

Consistent wear around the whole tire is normal. 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.

If your tires pass these tests, you may not need to buy new tires just yet. It’s a good idea to reassess the tread every few thousand miles, or once a month, and even more often if you’re putting a lot of wear on your vehicle or driving long distances.

When Should Your Tires Retire?

No matter how new your tire is, Bridgestone recommends checking inflation pressure every month and scheduling regular inspections with a pro. After five years, an inspection is essential to determine if a tire is still road-worthy.

We recommend tires that were manufactured 10 years prior (or longer) be taken out of service and replaced with new tires. Same goes for the spare. If it’s 10 years old, it needs to be replaced, even if it appears new.

It’s important to note that the age of a tire is not the only indicator of whether it needs to be replaced. Many tires will need to be replaced before 10 years of age due to routine tread wear and other conditions such as punctures, impact damage, improper inflation, overloading and more. If a tire is worn out or otherwise unserviceable from damage or conditions of use, it should be replaced regardless of when it was produced or purchased.

Do I Have To Replace All Four Tires At Once?

Another common tire-buying question is if it’s necessary to replace all four tires at once. The simple answer is yes. It is recommended to replace all four at once because your tires are key to the performance and handling of your vehicle, it’s important for them to be as identical as possible. If your tires don’t match, one end of your vehicle may not be able to respond as quickly as the other, making it difficult to control. Your tires are what keep your vehicle connected to the road, so having an even surface is vital.

If you are in a situation where you will be replacing fewer than four tires, select tires that are similar to what is currently installed on your vehicle. If you are replacing just two tires, those two tires should only be installed on the rear axle. You should only consider tires that are within the same category as your existing ones.

If you have a vehicle that came equipped with a staggered fitment (different size tires on the front and back) then you should check your vehicle owner’s manual for replacement recommendations.

Which Tires Are Better, New or Used?

There are a lot of risks associated with buying used tires. Since you don’t know the history of the tires, it can be difficult to know if they’ve been previously run under inflated, overloaded or have other unseen internal damage which could lead to an unexpected failure. Used tires might also have uneven wear, which can cause noise, vibration or other problems and may need to be replaced much sooner than new tires. It is best to replace tires with new tires of the same category, size, load capacity and speed rating as recommended by your vehicle’s manufacturer.

Check for Tire Recalls

When it comes to recalled tires, there is only one position to take.   We do not want anyone driving on recalled tires. We are committed to replacing, free of charge, any Bridgestone or Firestone tire (or other brands warranted by Bridgestone) subject to a customer satisfaction, quality and/or safety recall, at any time. The easiest way for consumers to get answers to questions about recalled tires is to call 1-844-293-7514 or locate an authorized Bridgestone or Firestone dealer to examine the tires in question. You can also check current tire recalls online at the National Highway Traffic Safety Administration site. 

Ask The Pros

There’s no reason to guess. Talk to a tire dealer or other authorized professional so you can make certain you’re choosing the best tire option for your vehicle. Find out if tire rotation and balancing are included with your new tires. If they are not, see if you can bundle the maintenance service. Ask the dealer to outline the manufacturer’s warranty and replacement options to make certain your new investment is protected in the long run, and inquire about any specials they may be offering. With these tire-buying tips and some trusted ratings in hand, you should be able to confidently pick out new tires.


Bridgestone consistently strives to connect with drivers through our stores, dealers and media campaigns to raise awareness and educate consumers on safe driving and tire safety. We encourage all consumers to learn all they can about tire safety and why it's important to have their tires, including the spare tire, regularly inspected by a qualified professional.

Position on Recall Awareness and Tire Age

Bridgestone Americas, Inc.

  • Bridgestone Americas has been very clear about our position on recalled tires: we do not want anyone driving on recalled tires from our company or any other company.  We are committed to replacing, free of charge, any Bridgestone or Firestone tire (or other brands warranted by Bridgestone) subject to formal recalls, at any time. The easiest way for consumers to get answers to questions about their tires is to call 1-844-293-7514 or locate an authorized Bridgestone or Firestone dealer to examine the tires in question.  
  • Our company continues to reach out to drivers through its stores, dealers and media campaigns to raise awareness and educate consumers on safe driving and tire safety. We encourage all consumers to go to www.bridgestoneamericas.com/safety.com to learn about tire safety and why it’s important to have their tires, including the spare tire, regularly inspected by a qualified professional.
  • Bridgestone recommends that tires more than 10 years old should be taken out of service and replaced with new tires. Be sure to check your spare tire and replace it if it is more than 10 years old, even if it appears new.
  • In addition, Bridgestone recommends that all tires be regularly inspected and that inflation pressures be checked monthly. In particular, tires should be inspected after five years to assure that they are in appropriate condition for further service.

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How to find your tire size? | Internet

So, you are planning to replace car tires - no matter for what reason, maybe the old tires are out of order or you are thinking of changing the appearance of your car - the first thing you will need to decide is to decide what size car tires are needed specifically for your vehicle. Only after that you will be able to choose a suitable tire model in the online store. Understanding the marking of rubber is not as difficult as it seems - just read the information in this article. nine0003

1. Numbers and letters on a car tire are important.

The vehicle type for which each tire is designed is indicated by numbers or letters on the tire. Typical tire operating conditions can be seen here.

Let's consider an example - size P 225/45R17 91S.

The letter "P" used on car tires indicates that the product is intended for passenger cars and is present in the P-metric system, which began to be used more than 40 years ago and is still in use today. Passenger cars include passenger cars, minivans, pickup trucks and light (parquet) SUVs. The carrying capacity of vehicles for which tires with the P mark are intended should be in the range from 250 to 500 kg per 1 wheel. nine0003

If the rubber marking does not start with a letter and three numbers, this means that this tire is made according to a different dimensional system - Euro-metric, which is common in European countries and applies to car tires for passenger cars, vans and light SUVs. The size range in the P-metric and Euro-metric systems is almost identical, the differences exist only in the ultimate load.

Consider another example - T125/90D16 98M.

Tire markings beginning with the letter T indicate that the tire is a spare tire and can only be used during tire fitting work on the main tire. nine0003

If the tire marking begins with the letter designation LT, this indicates that the product belongs to the Light Truck-metric size system, which is used to designate the size range of automotive rubber installed on large vehicles, pickups, vans, powerful SUVs with a load capacity of 750 up to 1000 kg.

If the marking of a car tire ends with the letter LT, this means that the tire belongs to one of three marking systems - flotation (Flotation), numerical (Numeric) or wide base (Wide Base). These systems apply to tire sizes for heavy trucks and trailers. For such vehicles, rim diameters start at 16.5 inches, with the help of a large tire, the car easily copes with the most difficult and difficult trails. In this category, you can pick up tires for cars weighing from 500 to 1000 kg. nine0003

In the Euro-metric system, the letter designation may come after the number, for example, the letter C in this example is /70R15C 104/102R. This means that this rubber is intended for use on commercial vehicles - trucks, trucks or vans. In addition to marking C, the letter designation B or D may be allowed, which also corresponds to a certain load range.

A tire label that begins with the letter ST, eg ST225/75R15, indicates that the tire is intended for general or special purpose vehicle trailers. Tires with this marking are not permitted on cars, trucks, vans and pickup trucks. nine0003

To more accurately determine the choice of tire sizes and the most suitable modification of rubber for your car, a specialist from our company GOOD WHEELS can always help you - just make a call to the indicated numbers or leave a request on the website - you will be given a detailed consultation on the model and size range. We recommend that you have at least basic knowledge in this area - this knowledge will always be useful to you and you can learn it by asking a consultant of our tire center. nine0003

2. What does the three-digit number combination mean?

Everything is much simpler here than with letter designations. The three-digit number after the letter indicates the size of the tire width in millimeters. For example - 225/45R17 91S. Here the number 225 is the width of the tire from outside to inside when measured directly on the wheel after installation.

3. The numbers after the profile size - what do they mean?

The next two digits indicate the numerical value of the ratio of the height of the tire to the width of the profile. For example, in this case - 225/45R17 91S figure 45 means that the height of the tire is 45 percent of the profile width. Height is measured from the outer edge of the wheel to the seat rim. That is, the higher the number, the larger the sidewall of the tire. If we know that the tire width is 225 millimeters, and the digital value is 45, then this means that the profile height is 101.25 mm. In another example - 225 / 70R16 - the ratio is slightly different, with a width of 225 mm, the height is 70 percent, that is, 157.5 mm.

4. Letter designation after the number indicating the percentage of the ratio of width and height. nine0007

In this example - 225 / 45R17 - the letter R indicates that the cords in the carcass are located radially, that is, the tire has a radial design. The radial type of tires is the most common and sold. More than 98 percent of all produced and sold car tires are of radial design.

Tires designed for light duty vehicles will use the letter D instead of the letter R. This tire will have a diagonal carcass type. nine0003

Tires marked B are practically non-existent and rarely produced - these are tires with a diagonal carcass and tread reinforcement with special belts. This design is called Belted and is a rarity in car shops and tire centers.

The letter Z can be added to the letter designation R - as in this example 225/45ZR17. Now it is rare to find tires with such a designation, but nevertheless, the speed index is displayed in this way - Z-speed rated. nine0003

The speed index can only appear after the numbers indicating the percentage of height to width ratio and after the letter R, indicating the type of internal tire construction - but this is rarely used, since 1991 the speed index marking has been indicated in the service description.

6. Tire and wheel diameter.

After the letter R (D or B), manufacturers indicate a number that indicates which rim diameter this tire fits. For example, in the marking P225 / 45R17 91S number 17 means that this rubber is intended for a disk with a diameter of 17 inches.

The numerical designation can be from 8 to 28 - what number, this should be the size of the disk to install this particular tire on it. Common designations are 8, 10, 12, 13, 14, 15, 17, 18, 19, 20, 23, 24, 26, 28. This size range allows you to choose tires for cars and trucks, minivans, vans, SUVs.

Less common but still used sizes are 14.5, 15.5, 17.5 and 19,five. These dimensions are suitable for heavy-duty trucks and covered vans.

Sometimes the size markings are given in millimeters, for example - 190/65R390. Such a system is called millimetric. Michelin uses this system for the TRX range.

Michelin also uses its own original integrated tire labeling system called the Michelin PAX. Under this system, tire dimensions and rim dimensions are indicated in millimeters. For example - 235 / 710R460A 104T, here 235 is the size of the profile width in millimeters, 710 is the outer diameter of the tire in millimeters, 460A is the rim diameter, the letter designation A means that the tire has asymmetric beads, with different diameter sizes. nine0003

Understanding the nuances of the manufacturer's label when purchasing new car tires, especially if these are ultra-modern tires created using the latest innovative technologies, can take forever. It will be even more difficult for an autolady to cope with the choice of rubber on their own than for a male driver. Perhaps you should not waste your time on this - after all, the specialists of the GOOD WHEELS online hypermarket are always ready to help you in choosing high-quality car tires! nine0003

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MILLIMETERS AND INCHES

The main "metrics" of the tire are hidden in a set of numbers printed on the sidewall. Take, for example, 195/65R15.

The first (195) indicates the width of the tire section in millimetres. The second (65), after the slash, is a series of tires. In fact, this is the height of its profile, indicated as a percentage of the width. In more familiar millimeters, it will be: 195 × 0.65 = 126.75.

The letter R indicates the radial design of the tire. And the last digit (15) indicates the landing diameter (not the radius!) of the tire in inches. Converting it to millimeters (15 × 25.4 = 381) and adding twice the height of the profile (or sidewall) in the same units (126.75 × 2 = 253.5), we get the main overall size of the tire - its outer diameter: 381 +253.5 = 634.5 mm.

The owner's manual will tell you which tires are suitable for your car. The lazy ones will find a label with allowable sizes and recommended pressure on the end of the driver's door or the B-pillar. nine0003

If the tire diameter is less than optimal, this will lead to a decrease in ground clearance, and the use of tires with a larger diameter is limited by the dimensions of the wheel arches. Rubber should not touch the body or chassis elements - especially when turning the wheels left and right and driving with a load on uneven roads. Any deviation of the diameter from the recommended one also affects the speedometer readings.

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If the car manufacturer allows you to vary the size of the tires within certain limits, please note that wider tires are preferable for summer: the wider the contact patch with the road, the better the tires cling to it. But the wider the tire, the greater the rolling resistance. In addition, on such tires, the car handles worse in small radius turns - the tread has to slip due to the fact that its opposite sides pass different paths. Another disadvantage of wide tires is the tendency to hydroplaning (loss of contact with a wet road). nine0003

The high sidewall softens bumps well, but makes the tire more pliable. When turning, it deforms and does not respond so quickly to taxiing. Therefore, in terms of handling and stability, a low profile tire is preferable. But it is stiffer and has less durable sidewalls.

In winter, on the other hand, the specific pressure in the contact patch should be higher, which improves grip on ice and snow. So, narrower tires are preferable here.

CHAMBER OF WEIGHS AND MEASURES

In the marking, as a rule, there are a couple more numbers that are rarely paid attention to, for example, 91H, 95T. These are indices of carrying capacity and maximum permissible speed. According to special tables, it is not difficult to convert them into specific values ​​of load (in kilograms) and speed (in kilometers per hour).

02-03-dop1

Here is an example calculation for a maximum speed of 185 km/h. We increase the figure by 15%, since such an increase is possible when driving on a long descent or with a strong tailwind. 185 x 1.15 = 209,3. This number according to table No. 1 is between the values ​​190 and 210. We round it up and get the index H.

). But in no case should you exceed the speed limit of tires - they will not withstand a large centrifugal force.

Now about the load capacity. The number 82, for example, indicates that the tire is capable of carrying a load of no more than 475 kg. Determine the minimum required for your vehicle based on the maximum axle load at its full weight. Divide this value by two and in the tables (they are shown in the photo gallery at the bottom of the article) select the nearest value, rounding it up. Some tire and car manufacturers recommend increasing the calculated value by 20%, creating some kind of margin. nine0003

illust_1r

SWAT

On some tires, this set is supplemented by some more symbols.

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XL is a pure bluff, designed to suggest that tires have an increased load capacity. But the real load is determined only by the index described above. nine0003

The symbols SUV or 4x4 (depending on the manufacturer) mean that the tires are designed for crossovers or all-terrain vehicles. Their main features are a more powerful frame and shoulders reinforced from the inside.

The letter C in the marking (for example, 185/75R16C) refers to light commercial vehicles (minivans and light trucks). Such tires are distinguished by a double index of load capacity (for example, 104/102Q), where the first digit indicates the load capacity of the wheel in a single-wheel version, and the second - in a two-wheel version. nine0003

Run-flat tires are able to cover some distance without losing air. They also have a distinctive marking, which is shown in the table (you will find it in the photo gallery below).

TO THE PIT, TO THE DITCH

There is an opinion that on bad roads it is better to use tires with a high speed index: they are supposedly stronger. There is an element of truth here. An additional reinforcing "padding" between the breaker and the carcass makes the tires a little less vulnerable to impacts. The payoff for this is increased rigidity, sometimes also noise. nine0003

In fact, in difficult conditions, tires with a higher load index are preferable. They not only have an additional backing, but also reinforced sidewalls.

Choosing tires: what do the codes on tires mean (INFOGRAPHICS)

How to choose the right tires for your car? In the off-season, for many drivers, this is the most pressing issue. The necessary information about the dimensions, speed and loading characteristics of tires can be easily found in the car's operating manual. Sergey Mishin, head of the tire test group of Za Rulem magazine, talks about how to navigate the tire markings and what threatens mistakes in choosing winter and summer tires. nine0138

Choosing tires: what do tire codes mean (INFOGRAPHICS)

Choosing tires: what do tire codes mean (INFOGRAPHICS)

How to choose the right tires for your car? In the off-season, for many drivers, this is the most pressing issue.


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