Matching tires and rims. Explanation of tire sizes in centimeters

Car owners use a tire calculator to select tires and rims of the right size. All calculations are done online. The user does not have to deal with lengthy, incomprehensible calculations. The application is multifunctional, since the motorist will be able to understand how to change the dimensions of the wheel, taking into account changes in the size of tires and wheels. Consider the features of using the service.

Tire calculator functionality

To help with the selection of tires suitable for a particular car in terms of size and characteristics, the tire selection calculator can. Vehicle owners resort to the services of the service when it is time to replace the tires and wheels on the vehicle. In order not to waste time on meaningless "changing shoes", checks, use the proposed online service. Tire calculator features:

• you can calculate the size of tires;
• the service provides different parameters - wheel diameters, changes in the height of the clearance between the road and the car (clearance), track expansion;
• help in converting inches to millimeters or vice versa, using the American and European size charts.

The tire calculator has been designed to speed up the selection of tires, making the procedure much easier. Since every owner of a car faced the difficulties of choosing, online calculators very quickly gained popularity among users.

How to use the tire calculator

There are several tips to help you use the tire size calculator for its intended purpose. Step-by-step instruction consists of the following steps:

1. In the form you will need to enter the size of the tires installed on the car, as well as those that you would like to install.
2. The user will see a special table with the results of calculations. From this data, it will be possible to find out which tires are needed for a particular vehicle.
3. After selecting tires, you can proceed to the calculation of the size of the disks. Here you will need to set the exact data - the maximum / minimum width of the disk installed on the car. All calculations will be performed automatically.
4. If you need to convert inches to millimeters, you can use the online converter. This action will allow you to find analogues with American sizes and with European ones. Comparison through the tire calculator will be as accurate as possible, since all the necessary information has been entered into the online service database.

The general selection procedure is very simple, but the owner of the car will definitely need to enter the initial data. The parameters should be as accurate as possible so that there are no errors or inaccuracies in subsequent results.

You can use this service on our website. The program is freely available, anyone can make calculations in a few minutes. To simplify the process of use, it is worth using the instructions given.

Good day, dear readers. Today I want to answer immediately a lot of questions related to wheel sizes. Many of my readers do not understand what they mean and why they are needed at all! Today I will try to explain in a simple and understandable language what the dimensions of rubber on cars mean ...

The dimensions of the rubber wheel contain a lot of useful information, you just need to be able to read it. Without this information, you will not be able to choose the right tires for your car, they simply will not fit in size. Although now on the bodies of many brands there are special plates with recommendations, you just read them and go to the store to buy the same ones. However, there are not always such plates and you need to determine the dimensions of the tires yourself! A small clarification, I will only talk about overall dimensions, there have already been many articles about other characteristics, links will definitely be below.

I will talk about them using the example of my winter wheels, KAMA EURO 519, it should be noted that they are in no way inferior to their foreign counterparts. Read informative.

To begin with, the overall dimensions

I have a wheel size R16 205/55 , these are the so-called dimensions. Rubber is considered low profile (more).

The notorious letter R

Many mistakenly think (to be honest, I thought so too) that the first English letter R - means the abbreviation "RADIUS"! But it's not! The letter R means radial tire, read the article -. This is such a method of assembling rubber and metal cord during production. Of course, you can also meet the letter D in front (diagonal), but such a designation is now really rare. In fact, this letter has nothing to do with size. Let's go further...

Disc diameter

The second number (in this case we have 16) indicates the diameter of the hole in the rubber, or which disc you can put this rubber on. We have 16, which means it's 16 inches! Remember that this size is always given in inches (1 inch = 25.4 mm). if we knock out our size, it turns out - 16 X 25.4 mm = 406.4 mm. The disc cannot be larger or smaller than the diameter of the wheel, you simply cannot put it on. That is, if the rubber is 16 (406.4 mm), then the disk should be 16 (406.4 mm).

Width

A large number almost always characterizes the width. In this case, this figure is 205. It is measured in millimeters, that is, the width of my wheel is 205 mm. The wider the rubber, the wider the track, respectively, the patency and adhesion increases.

Cord height

This is the smaller number that is applied through the fraction. In my case, this is 55, measured as a percentage of the width (of the larger number). What does it mean? To find the height (in my case) you need to calculate 55% of 205 mm. Thus it turns out:

205 X 0.55 (55%) = 112.75 mm

This is the height of the cord of our rubber, also an important indicator, see the figure.

Total wheel height

Let's calculate the total height of my wheel. What happens.

Rubber cord 112.75 X 2 (since the height is on both sides, top and bottom) = 225.5 mm

Under the disk 16 inches = 406.4

Total - 406.4 + 225.5 = 631.9

Thus, my wheel is a little more than half a meter high, namely 0.631 meters

Let's look at the most common tires that are used by most cars, there are three of them - these are R13, R14 and R15

Tire sizesR13

The most common of all isR13175/70 such are installed on many models domestic VAZ(although now departing).

What happens:

R13 - diameter 13 inches (multiply by 25.4) = 330.2 mm

Width 175

Height - 70% of 175 = 122.5

Total - (122.5 X 2) + 330.2 \u003d 574.2 mm

Tire sizesR14

One of the most common isR14175/65, are also installed on domestic VAZ models, more recent years of production, such models as Priora, Kalina, Grant, as well as on some inexpensive (folk) foreign cars - for example Renault Logan, Kia Rio, Hyundai Solaris etc.

What happens:

R14 - 14 inch diameter (multiply by 25.4) = 355.6 mm

Width - 175

Height - 65% of 175 = 113.75

Overall dimensions - (113.75 X 2) + 355.6 mm = 583.1 mm

Tire sizesR15

The most common example is -R15 195/65, installed on many foreign cars (folk) class, but in high trim levels.

What happens:

R15 - diameter 15 inches (multiply by 25.4) = 381 mm

Width 195

Height - 65% of 195 = 126.75

Total - (126.75 X 2) + 381 \u003d 634.5 mm

As you can see, it is not so difficult to calculate the size of the rubber.

Of course, there is still other useful information on the wheel, I have already written articles about it below. For you I will list the points, read useful and interesting:

In general, read the heading - there is much more information there. As you can see, all this information can be read from the tire, sometimes you can’t even believe it!

When choosing new wheels for a car, the question often arises, should I put wheels larger or smaller, or in order to improve appearance auto or cheaper purchase of tires and wheels. But the most main question whether the wheels are suitable for my car and how its characteristics will change. You can understand whether the wheels will fit on the gas tank cap or the side stand of the car (photo 1). Or find your car in our directory of applicability of discs to cars, and see the tires recommended by the factory. But it often happens that you can put other tires that are not officially approved by the factory.

In this case, the main thing is to understand how the speedometer will change, i.e. the speed of the machine, as the outer radius of the wheel will change. The clearance will also change ( ground clearance). It is not recommended to go beyond the values ​​of factory tires by more than 2-3%. The handling and behavior of the car, the consumption of gasoline and the actual speed of the car may change.

Tire calculator - size comparison

Our tire calculator will show you visual differences in tire diameter, profile, radius, ground clearance and width. Dashed lines show the difference in size. At the top, you can see a visual representation of the old tire (original size), and at the bottom, a visualization of the new tire. Just as you noticed, the tire can be seen in lateral and frontal projection. You can copy the URL of the page and show it to other people and they will see the same comparison as you see.

But how to understand all these values ​​\u200b\u200band the difference in%? To do this, we created a tire calculator, it will help you understand the change in all the necessary characteristics and show the difference in% between the old and new tires, and even visually display how the wheel of the old and new sizes will look like. You just need to enter the tire width, profile and wheel radius. Usually they are displayed in this form - 195 \ 65 R15 (photo 2).

How to use the online tire calculator?

Using our online tire calculator is very easy. In the upper left corner of the site, there are fields for choosing a tire size. In the top row, you need to indicate the size of your original factory tire (or the tires that are currently installed on your car). These values ​​are written on the tire profile (side surface). In the first list, you need to select the tire width - it is indicated in millimeters. The second list is the percentage of profile height to tire width. The third list is the disc diameter in inches (commonly referred to as the radius).

In the bottom row you need to specify the size of the new tires. Tires that you are going to install on a car or have already bought. Then click "Calculate". Our tire calculator will calculate the differences between the old and new tires and display them in a table and a picture. Namely: diameter, width, circumference, tire profile height, number of revolutions per kilometer and change in car clearance. The first columns of the table will show the parameters for old and new tyres, the following columns will show the difference in mm and the percentage difference between them.

There is a speedometer at the bottom of the tire calculator to visually compare the speed of the old and new tires. Under the speedometer, you can speed up and slow down and see changes in speed difference between old and new tire.

Be careful!

Be careful on the road and follow the manufacturer's recommendations. The reverse side of the installation is not standard sizes tires, this is the risk of losing insurance in case of an accident, not passing the state technical inspection of the car, since the setting of tires that are not approved by the factory is considered a change in the design of the vehicle.

Tires of American and European production differ in marking. Often a situation arises when it is necessary to convert inches to centimeters. In this article, we will describe how to decipher tire sizes in centimeters.

Metric tire marking

The main dimensions of tires are prescribed by marking, these include:

1. Tire profile width - the distance, expressed in millimeters or inches, between the outer sides of the sidewalls of an inflated tire, excluding elevations, trim or belts. The specified value should not exceed the product rim width by more than 30%.
2. Tire series. Specifies the ratio of the width and height of the product profile. Allows you to distinguish rubber in this way:

• low profile - series less than 70%;
• high profile - in the range of 70-82%;
• full profile - more than 85%.

1. Tire construction. There are radial and diagonal tires. In the first case, the fibers of the cord layer are placed perpendicular to the circumference of the wheel. In the second variant, the cord threads are overlapped. Radial tire construction is more common, these tires provide better grip wheels with road surface, they are more reliable in operation.
2. wheel radius.

How to understand what tire markings mean? The designations on the side of automobile rubber are applied by tire manufacturers. Factory marking is in metric or inch system. For example, the size of tires marked with the metric system 265/75 R15 corresponds to the designation of the inch system 31 × 10.5 R15. The interpretation of these designations in centimeters means:

1. The designation 265/75 R15 indicates the dimensions of the tire:

• 265 - a figure that determines the width of the tire (one centimeter is equal to ten millimeters, 265 mm = 26.5 cm);
• 75 is the percentage (75%) that determines the relationship between the height of the tire profile and the width of the rubber (265 * 0.75 \u003d 198.8 mm or 19.9 cm), the number found indicates the height of the tire profile;
• R - denotes the radial type of tires;
• 15 - wheel diameter, the size is indicated in inches, you can convert the indicated parameter into centimeters by multiplying the digital value of interest by 2.54, since 1 inch is 2.54 cm, as a result we get 15 * 2.54 \u003d 38.1.

1. The designation 31 × 10.5 R15 stands for:

• 31 - wheel height (31 inches or 31 * 2.54 = 78.7 cm);
• 10.5 - tire width (10.5 inches or 10.5 * 2.54 \u003d 26.7 cm);
• R - indicates the radial type of tires;
• 15 - determines the diameter of the wheel (15 inches or 15 * 2.54 = 38.1 cm).

• subtract its radius from the total height of the tire (78.7-38.1 \u003d 40.6 cm);
• divide the resulting value by 2 (40.6 / 2 \u003d 20.3 cm).

Differences in the marking of tires

When deciphering tire sizes, pay attention to the letter in front of the tire dimensions:

1. "P" - indicates the "P-metric" system used for minivans, light pickups (with a carrying capacity of up to 0.5 tons). This system is very convenient, it is often used by tire manufacturers.
2. "T" - "spare" tires are marked with the indicated letter: rubber can be used until the main tire is repaired or replaced.
3. "LT" stands for "Light Truck-metric" system, designed for trucks and vehicles capable of transporting large loads. Vehicles with a load capacity of up to 1 ton fall into this category.
4. "ST" - indicates "Special Trailer Service", products are designed for trailers, they can also be used to transport boats or cars.

Letter values ​​can be at the end of the tire marking, in which case they mean:

1. "LT" - the tire refers to products with early marking:

• "Numeric" - numerical, tires are designed for vehicles transporting heavy loads, trailers
• "Wide Base" - tires with a wide base, manufacturers make such products with a rim diameter of 16.5 inches;
• "Flotation" - flotation, large-sized tires that allow the car to move on a sandy surface or mud.

1. "C" is a commercial tire used for vans and distribution vehicles capable of transporting large loads.

If at the beginning of the marking there is no letter designation and a three-digit number, for example, 45R15, then this is a tire with a metric size of the Euro-metric system applicable on tires of European manufacturers. The indicated dimension corresponds to the decoding according to the P-metric system, but differs in smaller loads.

• 235 - product width (235 mm = 23.5 cm);
• 710 is a number indicating outside diameter tires (710 mm = 71.0 cm);
• 460 - tire rim diameter (460 mm = 46 cm);
• A - the designation of asymmetric rubber sides, for example, 460A means that the outer side has a diameter of 45 cm, and the inner one is 47 cm.

Such non-standard markings are designed for vehicles with wheels of a specific size that differ in side profiles from standard metric or inch products. Faced with non-standard markings, it is better to find out their decoding from the tire manufacturer.

Comparison of calculated data

Independent decoding of tire sizes requires a certain accuracy of calculations. You can check whether the conversion from centimeters to inches and vice versa is correct using tire calculators. With their help, you can also find out how many tire sizes are suitable for a particular car model.

Tire calculators are easy to find on the Internet, they usually have American and European systems of sizes at the same time. Therefore, by entering the tire sizes recommended by the car manufacturer in the metric system, it is possible to get a list of American and European tires. It is very convenient, if necessary, to select the brand of rubber of interest, as well as view the possibility of changing tire sizes recommended by the manufacturer. When using tire calculators, it is necessary to take into account the error arising from rounding, so it is better to translate the dimensions of interest manually, then compare them with the options calculated by the Internet resource.

Conclusion

The American marking of rubber, if you do not take into account the inches that are unusual for us, is very convenient to use. But in most situations, you have to deal with the metric notation. Converting inch dimensions to centimeters is not difficult if you understand the decoding of the designations applied by manufacturers to the side surface of tires. In this case, it is necessary to take into account the error of calculations, which may arise due to inattention or rounding of the obtained values. To correctly calculate the dimensions, it is better to use the manual method, then compare the obtained parameters with the data of tire calculators. We do not recommend using only one method, since there is also a certain rounding error in the embedded electronic computing programs.

Do you want to choose a tire for your car, but do not understand tire markings well? It's not a problem! In this section, we will help you figure out what tire parameters are, what they mean, and which tire is right for your car.

Deciphering tire markings.

195/65 R15 91 T XL

195 is the tire width in mm.

65 - Proportionality, i.e. profile height to width ratio. In our case, it is equal to 65%. Simply put, with the same width, the larger this indicator, the higher the tire will be and vice versa. Usually this value is called simply - "profile".

Since the tire profile is a relative value, it is important to consider when choosing rubber that if you want to put tires with a size of 205/65 R15 instead of the size 195/65 R15, then not only the width of the tire will increase, but also the height! Which in most cases is unacceptable! (except when both of these sizes are indicated in the car's operating book). You can calculate the exact data on changing the outer dimensions of the wheel in a special tire calculator.

If this ratio is not indicated (for example, 185/R14С), then it is equal to 80-82% and the tire is called full profile. Reinforced tires with this marking are usually used on minibuses and light trucks, where a large maximum wheel load is very important.

R- means a tire with a radial cord (in fact, almost all tires are made this way now).

Many mistakenly believe that R- stands for the radius of the tire, but this is precisely the radial design of the tire. There is also a diagonal design (indicated by the letter D), but recently it has practically not been produced, since it performance characteristics noticeably worse.

15 - diameter of the wheel (disk) in inches. (It is the diameter, not the radius! This is also a common mistake). This is the “landing” diameter of the tire on the disk, i.e. is the inside size of the tire or the outside of the rim.

91 - load index. This is the level of maximum permissible load on one wheel. For passenger cars, it is usually done with a margin and is not a decisive factor when choosing tires (in our case, IN - 91 - 670 kg.). For minibuses and small trucks, this parameter is very important and must be observed.

Tire load index table:

T- tire speed index. The larger it is, the faster you can drive on this tire (in our case, IS - H - up to 210 km / h). Speaking about the tire speed index, I would like to note that with this parameter, the tire manufacturer guarantees the normal operation of the rubber when the car is constantly moving at the specified speed for several hours.

Speed ​​index table:

American tire markings:

There are two different markings for American tires. The first one is very similar to the European one, only the letters “P” (Passanger - for a passenger car) or “LT” (Light Truck - light truck) are placed before the size. For example: P 195/60 R 14 or LT 235/75 R15. And another tire marking, which is fundamentally different from the European one.

For example: 31x10.5 R15(corresponds to European size 265/75 R15)

31 is the outside diameter of the tire in inches.
10.5 - tire width in inches.
R- a tire of a radial design (older models of tires were with a diagonal design).
15 is the inner diameter of the tire in inches.

Generally speaking, except for inches that are unusual for us, the American tire marking is logical and more understandable, unlike the European one, where the height of the tire profile is not constant and depends on the width of the tire. And here everything is simple with decoding: the first digit of the standard size is the outer diameter, the second is the width, the third is the inner diameter.

Additional information indicated in the marking on the sidewall of the tire:

XL or Extra Load- Reinforced tire, the load index of which is 3 units higher than that of conventional tires of the same size. In other words, if a given tire has a load index of 91 marked XL or Extra Load, then this means that with this index, the tire is able to withstand a maximum load of 670 kg instead of 615 kg (see the table of tire load indices).

M+S or M&S tire marking (Mud + Snow) - mud plus snow and means that the tires are all-season or winter. Many summer tires for SUVs are labeled M&S. However, these tires must not be used in winter time, because Winter tires have a completely different rubber compound and tread pattern, and the M&S badge indicates good tire flotation.

All Season or AS all season tires. Aw (Any Weather) - Any weather.

Pictogram * (snowflake)- rubber is designed for use in harsh winter conditions. If this marking is not on the sidewall of the tire, then this tire is intended for use only in summer conditions.

Aquatred, Aquacontact, Rain, Water, Aqua or pictogram (umbrella)- special rain tires.

outside and inside; asymmetric tires, i.e. It is important not to confuse which side is the outside and which is the inside. When installing, the Outside inscription must be on the outside of the car, and Inside on the inside.

RSC(RunFlat System Component) - RunFlat tires are tires on which you can continue driving a car at a speed of no more than 80 km / h with a FULL pressure drop in the tire (due to a puncture or cut). On these tires, depending on the manufacturer's recommendations, you can drive from 50 to 150 km. Different tire manufacturers use different designations for RSC technology. For example: Bridgestone RFT, Continental SSR, Goodyear RunOnFlat, Nokian Run Flat, Michelin ZP, etc.

rotation or arrow this marking on the sidewall of the tire indicates a directional tire. When installing the tire, you must strictly observe the direction of rotation of the wheel, indicated by the arrow.

Tubeless - tubeless tire. In the absence of this inscription, the tire can only be used with a camera. Tube Type - indicates that this tire must be used only with a tube.

Max Pressure; maximum allowable tire pressure. Max Load - the maximum allowable load on each wheel of the car, in kg.

Reinforced or the letters RF in the size (for example 195/70 R15RF) means that this is a reinforced tire (6 layers). The letter C at the end of the size (for example 195/70 R15C) indicates a truck tire (8 layers).

Radial - this marking on the rubber in the standard size means that this is a radial tire design. Steel means that there is a metal cord in the tire structure.

Letter E(in a circle) - the tire meets the European requirements of ECE (Economic Commission for Europe). DOT (Department of Transportation - US Department of Transportation) is an American quality standard.

Temperature A, B or C heat resistance of tires at high speeds on a test bench (A is the best indicator).

Traction A, B or C- the ability of the tire to brake on a wet roadway.

Treadwear; relative expected mileage compared to a specific US standard test.

TWI (Tread Wear Indication)- Tire tread wear indicators. The marking on the TWI wheel can also be with an arrow. Pointers are located evenly in eight or six places around the entire circumference of the tire and show the minimum allowable tread depth. The wear indicator is made in the form of a protrusion with a height of 1.6 mm (the minimum tread value for light vehicles) and is located in the tread recess (usually in the drainage grooves).

DOT- Encoded manufacturer's address, tire size code, certificate, issue date (week/year).