Comparison of wheels by parameters. Tire sizes – popular misconceptions and reality. Changing the diameter of the disk

Do you want to choose a tire for your car, but are not well versed in tire labeling? No problem! In this section, we will help you figure out what tire parameters are, what they mean, and which tire is suitable for your car.

Decoding tire markings.

195/65 R15 91 T XL

195 is the width of the tire in mm.

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

Since the tire profile is a relative value, it is important to take into account when selecting tires that if instead of size 195/65 R15 you want to install tires with size 205/65 R15, then not only the width of the tire will increase, but also the height! Which is unacceptable in most cases! (except for cases when both of these standard sizes are indicated in the car’s operating book). Accurate change data external dimensions You can calculate the wheels using a special tire calculator.

If this ratio is not specified (for example, 185/R14C), 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 load on the wheel is very important.

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

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

15 - wheel (disk) diameter in inches. (It’s the diameter, not the radius! This is also a common mistake). This is the “fitting” diameter of the tire on the disk, i.e. This inner size tires or external at the disk.

91 - load index. This is the level of maximum permissible load on one wheel. For passenger cars, it is usually done with a reserve and is not a decisive value when choosing tires (in our case, ID - 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 higher the speed you can drive on a given tire (in our case IS - N - up to 210 km/h). Speaking about the tire speed index, I would like to note that with this parameter the tire manufacturer guarantees normal work rubber while constantly moving the car at the specified speed for several hours.

Speed ​​index table:

American tire markings:

There are two various markings American tires. The first one is very similar to the European one, only the letters “P” are placed in front of the standard size (Passanger - for passenger car) or "LT" (Light Truck - light truck). 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 - outer diameter of the tire in inches.
10.5 - tire width in inches.
R- a tire with a radial design (older tire models had a diagonal design).
15 - inner diameter of the tire in inches.

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

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

XL or Extra Load - a 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, this means that with this index, the tire can withstand a maximum load of 670 kg instead of 615 kg (see table of tire load indexes).

M+S or M&S tire marking (Mud + Snow) - mud plus snow and means that the tires are all-season or winter. On many summer tires for SUVs, M&S is indicated. However, these tires cannot be used in winter time, because winter tires have a completely different rubber composition and tread pattern, and the M&S badge indicates good performance cross-country ability of the tire.

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

Pictogram * (snowflake)- rubber is intended for use in harsh conditions winter conditions. If there is no this marking 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; asymmetrical tires, i.e. It is important not to confuse which side is external and which internal. When installing, the inscription Outside should be on the outside of the car, and Inside should be on the inside.

R.S.C.(RunFlat System Component) - runflat tires- these are tires on which you can continue driving a car at a speed of no more than 80 km/h with a COMPLETE drop in tire pressure (due to a puncture or cut). On these tires, depending on the manufacturer's recommendations, you can drive from 50 to 150 km. Various manufacturers tires use different RSC technology designations. 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 a tire, you must strictly observe the direction of rotation of the wheel indicated by the arrow.

Tubeless- tubeless tire. If this inscription is missing, the tire can only be used with a tube. Tube Type - means that this tire must be used only with a tube.

Max Pressure; maximum permissible tire pressure. Max Load - the maximum permissible load on each vehicle wheel, in kg.

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

Radial - this marking on the tire in the standard size means that it is a tire of radial design. Steel means that the tire has a metal cord in its construction.

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) - 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 road surface.

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

TWI (Tread Wear Indication)- indicators of tire tread wear indicators. The marking on the TWI wheel may also include an arrow. The indicators are located evenly in eight or six places around the entire circumference of the tire and indicate the minimum permissible tread depth. The wear indicator is made in the form of a protrusion with a height of 1.6 mm (the minimum tread size for light cars) and is located in the tread recess (usually in the drainage grooves).

DOT- Manufacturer's encoded address, tire size code, certificate, production date (week/year).

To simplify the determination of tire size, a special tire calculator was developed, allowing the user to do without the need to decipher the digital values ​​​​on the side surfaces of the rubber. Using such a calculator, the difference in tire sizes, profile height and other parameters are determined. In addition, such a calculator allows you to obtain other related information, for example, on deviations in the speedometer, changes in ground clearance, and so on.

Purpose of the visual tire calculator

A visual calculator allows every car owner to easily determine the tire size and width of the required rims. With its help, it is possible to determine the diameter of the wheels, the error of the speedometers, the increase in the road track and changes in the clearance under the bottom of the car. Using a tire calculator, it is extremely easy to determine optimal size, suitable for a specific car model. The built-in size conversion system allows you to instantly transform values ​​from the inch system to the meter system and vice versa.

It is advisable to take advantage of the potential of the calculator in cases where the car owner switches to using tires and wheels of a different size from the original one. It allows you to visually determine the main dimensions and then model them for the selected car. In turn, it is impossible to select tires using it, since initially it does not provide for division by manufacturer.

Selection and comparison of tires according to calculator 2.0

In the case of installing new wheels and tires of a different size, based on the data received from the calculator, it is advisable to additionally carry out a number of measurements. It is advisable to determine the distance on the inside between the wheel and the suspension, as well as from the tread to the shock absorber cup. In addition, you will need to measure the distance between the tread, fender and steering rods.

In turn, when choosing new tires, it is necessary to proceed from the advisability of a slight deviation in geometric dimensions new tires from previously used ones. A significant size will cause instability in the movement of the car.

Each car is initially created to certain parameters and dimensions. This fully applies to the permissible size of the wheels and tires used. Accordingly, the selected tire models must be within the established limits. The use of a tire calculator allows you to simplify the selection process as much as possible depending on the specific vehicle.

Russians have to regularly deal with replacing tires, primarily seasonal ones. The simplest solution in this situation is to use rubber of similar size. If the tire size is maintained, the wheel will also retain its original dimensions.

In cases where tires of a different size are selected, the selection of appropriate disks is required to obtain a wheel with the required dimensions. At the same time, by changing the standard tire sizes, it is possible to control the driving characteristics of the car, adding additional softness or hardness. The higher the profile used, the softer the car feels on the road. As the profile decreases, rigidity increases, and narrow tires give more grip on snowy surfaces, so they look more advantageous on winter roads.

At the same time, when selecting the size of tires and wheels, you must adhere to permissible sizes. For example, tires that are too wide will touch the wheel arches while moving, rubbing them, and wearing out intensively on their own. It is also worth taking into account the fact that changing the size of the wheels affects the operation of the speedometer, in particular the magnitude of the error.

From the outside it may seem that the variety of available configurations greatly complicates the calculations, but the tire calculator greatly simplifies the selection process using 3D modeling. The correct selection of tires is not only necessary safety, but also optimization road possibilities car. At the same time, the presence of a metric and inch size system allows you to work without problems with both American and European standard sizes.

In the life of every experienced car owner with experience active driving vehicle from 3-5 years old, there were situations when he needed to pick up a wheel rim. However, it is not always possible to carry out this procedure based on the available parameters and geometric characteristics, because the disk itself may not be at hand. IN similar cases Car owners often find it helpful to know the size of their tires, since using these numbers it’s easy enough to select the product you’re interested in.

Many car enthusiasts who are preparing to buy new wheels to replace worn-out, damaged ones, or simply in connection with seasonal “change of shoes”, often ask the same question - how to choose wheels for tires according to the tire size?

Tire size on label

To answer this question, you need to know the general parameters by which these two products are inextricably linked, in particular:

• The radius must be the same for both the disc and the tire, because this parameter always determines the matching of the discs and tires, as well as their compatibility. So, the most popular wheel sizes are the range from R13 to R20, where the number shows the diameter in inches, but many car enthusiasts mistakenly consider this value to be the radius.
• The width of the rims corresponds to the same size on the tire, which can only fluctuate slightly. This dimension on the wheel is designated by the letter J, preceded by its value in inches. So, for example, the range 5.0J-6.0J corresponds to a tire width of 175 mm, 5.5J-7.0J - 215 mm, 6.0J-7.5J - 225 mm, and 7.0J-8.5J - 245 mm. Thus, the width of the rims and the width of the tires are absolutely interrelated indicators.
• The next important indicator is the rubber profile, which determines the overall size of the wheel assembly. So, for example, for the radius R17 on the Lada Kalina, you can install tires with a profile height from 40 to 45 mm, because the wheel arches and suspension structures are designed only for such a maximum size, and, for example, with the same dimension on Toyota Land Cruiser 200 will easily fit a profile with a height of 100 mm.
• Recently, rubber has only been produced tubeless, because the danger of an accident in the event of a puncture is minimal, and the edges of the tire, as well as the sides of the rim, have special rigid ribs that completely eliminate the passage of air after the rubber and steel come into contact. However, with tube tires, you need to look for wheels that fit it, and this is very problematic.
• Those cars that actively drive off-road often use devices such as beadlocks - powerful bolted steel discs installed on the inside of the wheel and pressing the rubber. These devices prevent the tire from spontaneously falling off the wheel rim even in cases where it can no longer maintain pressure due to an accident.

Most best option when purchasing a disc, have the tire itself available or at least know all its characteristics and be ready to always find it in a search engine on the Internet so that the seller can correctly select for his client the disc he is interested in with the optimal parameters.

Wheel to Tire Ratio Table

To make it easy for the driver to decide on the selection of wheel sizes based on his existing tire parameters, below is a table of the most common geometric characteristics wheels:

How to choose the right rim width

When choosing the width of the rims, the driver should adhere to certain rules, because there are some inconsistencies in the international designation of dimensions.

First of all, you should not be mistaken in the different system of units, because the width of the rim of a disk is determined in inches, while the width of a tire is indicated in millimeters. So, in order to compare numerical indicators, you need to multiply each inch by 23.5 mm.

Also, the buyer should not be confused by the fact that several wheel sizes can be suitable for a tire of the same width. This is due to the fact that the rubber product is elastic and can be deformed at the interface with the disk by several centimeters.

When choosing a disk, you need to remember that a wheel that is too narrow can cause the tire to fall off, since during pressure build-up it will expand more and more, and the sides of the steel product may not be able to hold it at a certain moment.

On the contrary, a disc that is too wide can be damaged, since the side profile of the rubber will not protect it from negative external influences, especially when driving off-road or in deep snow.

Disc for use only in summer period it can be wider so that the car looks more impressive on the highway or in a big city, but in winter, on the contrary, narrower, because the powerful side parts of the rubber should protrude as much as possible.

If a car enthusiast chooses stamped wheels and is preparing to protect them with caps, he should know that the plastic or rubber linings also have thickness, and so that the wheel does not look like it has a negative offset, he should choose its smallest width, based on the table values ​​​​given above.

Many large points of sale of such products often have special calculator programs combined with an electronic database for recording goods in the warehouse. Thus, the car enthusiast only needs to provide the parameters of his tires, which the seller immediately enters into the program as initial data, and a list of optimally suitable products available is displayed on the screen.

How to choose the wheel size according to the tire size

Which wheels fit which tires and vice versa? In order for the driver to be confident in the correct choice of the disc he is interested in and not regret the useless purchase later, he must take into account the following features of this product when looking for the right thing for himself:

• The radius of a tire is determined not by its outer contour, but specifically by the seat size at the location of the hard beads for installation on the rim. So, if it is not possible to determine its size on a worn-out product, you just need to measure the internal diameter and divide the resulting number by 23.5 mm to convert the figure to inches.
• Rubber with the Ran Flat function, often included with sports cars or with those European brands whose developers special attention They did not pay attention to practicality when replacing a flat tire, but to the free space in the trunk; it has very rigid sides and internal transverse stiffening ribs. This means that the disc must be selected from a high-strength metal, preferably forged, because these hard ribs can easily deform it during prolonged driving on a damaged tire.
• The same can be said if the outer radius of the tire differs little from the inner radius due to the profile being too low. So, when driving on an uneven road, there will always be an impact on the outer surface of the rim, because the softening effect from the air buffer is minimal.
• When choosing a wheel for a minibus, full-size SUV or pickup truck, that is, a vehicle that can be subject to significant loads, unlike passenger car, it is important to consider the maximum weight index on the tire. This means that if the wheel can be inflated to 2.7-3 atm, and it will be operated under a constant load of 1 ton or more, then the disk itself must also be reinforced, otherwise normal use of the wheel assembly simply will not work.

If the inner rim of the wheel has a radius of R17 or more, it is imperative to use only a cast or forged wheel as the main wheel. This is due to the fact that relatively thin sheets of stamping are unstable and susceptible to damage when moving, sharp maneuvers or encountering obstacles during long-term operation of the vehicle. In the case of a spare tire, after 1-2 uses for the entire period of operation of the car, it is unlikely that anything will happen to the product.

The main mistakes car enthusiasts make when choosing wheels

Not every driver can choose exactly the product that is optimal for his car the first time. Comparing disks by parameters is far from the final procedure, after which you can safely purchase the product. Thus, returns often occur at retail outlets because potential buyers make mistakes.

Regardless of the size and type of tire, a disc may fit perfectly on it, but not fit on the hub. This means that information about the mounting unit is as necessary as information about the tire size, because there are two most important indicators specific to a particular car model. These parameters are drilling, that is, the diameter of the mounting hole in the disk, and bolt pattern is the number of studs and the length of each of them. Without knowing these parameters, the mistake of buying an unnecessary product is very likely, since there are many variations.

People often take a disk with the maximum allowable width and do not monitor the ET indicator - offset, and also do not compare disks. So, this characteristic, for example, ET20, 25, 30, 35, 40, means the distance in millimeters from the point of attachment of the product to the hub to the extreme plane of the disk flange.

In order to choose the correct disc offset, you don’t need tire sizes at all, since what is important here is the size of the wheel arch and how deep the hub is beyond the transverse dimensions of the car.

If these parameters are incorrectly determined, motorists often encounter the fact that the rubber touches the wheel arches when driving, cornering, or while driving on a bad road and, accordingly, interferes with the active operation of the shock absorbers. In addition, the wheel may begin to protrude outside the car, which will inevitably pollute the body in rainy weather without installing additional wheel arch liners around the perimeter of the wheel arch. There is also a risk of damage to the discs when parallel parking the car near curbs.

In order to avoid these mistakes, car enthusiasts should study all technical parameters not only your tires, but also the car itself, using the owner's manual or consulting with experts in this field.

Before choosing a car, you need to use a special calculator yourself, since many sites have such a system to help car enthusiasts. So, for example, using the link you can enter the make of the car, its model, modification, year of manufacture, VIN number, tire sizes and other known parameters, and the system will absolutely accurately determine all ranges of wheels that will probably fit without any modifications or problems with the hubs specific “iron horse”.

In addition, such portals immediately contain information about which brands produce and sell these wheels and at what price, which will help the buyer finally decide on a purchase and not regret it later.

When selecting new wheels for a car, the question often arises: should I get larger or smaller wheels, or for the purpose of improvement? appearance cars or cheaper purchases 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 find out whether the wheels will fit on the gas tank cap or the side pillar of the car (photo 1). Or find your car in our directory of wheel applicability for cars and see the tires recommended by the factory. But it often happens that you can supply other tires that are not officially approved by the factory.

In this case, the main thing is to understand how the speedometer indicators will change, i.e. the speed of the car, since the outer radius of the wheel will change. The clearance will also change ( ground clearance). It is not recommended to go beyond the factory tire values ​​by more than 2-3%. The vehicle's handling and behavior, gas mileage, and actual vehicle speed may change.

Tire calculator - size comparison

Our tire calculator will show you visual differences in tire diameter, profile, radius, ground clearance and tire width. The dotted lines indicate the difference in size. At the top you can see a visual representation old tire(original size), and the new tire is visualized at the bottom. Just as you noticed, the tire can be seen in the side and frontal projections. You can copy the page address and show it to other people and they will see the same comparison as you see.

But how to understand all these values ​​and the difference in %? For this purpose, we created a tire calculator; it will help you understand the change in all the necessary characteristics and will show the difference in % between the old and new tire and even visually display what the old and new size wheel 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?

Our online tire calculator is very easy to use. In the upper left corner of the site, there are fields for selecting the tire size. In the top row you need to indicate the size of your original factory tire (or the tires currently installed on your car). These values ​​are written on the tire profile (sidewall). In the first list you need to select the tire width - it is indicated in millimeters. The second list is the percentage of the profile height to the tire width. The third list is the diameter of the disk in inches (commonly called radius).

In the bottom row you need to indicate the size of the new tires. Tires that you are going to install on your car or have already purchased. After that, click "Calculate". Our tire calculator will calculate the differences between the old and new tire and display them in a table and picture. Namely: diameter, width, circumference, tire profile height, number of revolutions per kilometer and change in vehicle clearance. The first columns of the table will show the parameters for old and new tires, 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 for visual comparison speed of the old and new tire. Under the speedometer, you can increase and decrease the speed and see the changes in the speed difference between the old and new tire.

Be careful!

Be careful on the road and follow the manufacturer's recommendations. The downside of installing non-standard tire sizes is the risk of losing insurance in the event of an accident and not passing a state vehicle inspection, since installing tires that are not approved by the factory is considered a change in the design of the vehicle.

Some things sound boring and are difficult to remember, but you need to know them. Especially for car enthusiasts. Especially those who consider themselves experts and have their own opinion on any subject. The devil is in the details, and this article is about one such detail.

There is no radius on a tire

Many people now won’t even understand what I’m getting at. “Well, radius, so what? I have 195-65R15 wheels, radius 15, it’s all written down, why are you being clever?!” That's what I'm being smart about. R15 has nothing to do with radius. Neither R nor 15.

Nowadays you can find a lot of information on the Internet, but such little things as the marking of car tires are not among the most popular. We’d rather discuss engine power or the number of goodies in the cabin, right? And we’ll leave the choice of wheels to the store manager. Well, or we’ll ask a friend. He definitely knows! He already has his third car!

In fact, it won’t hurt to understand these boring numbers even just for general development. Moreover, this will both help save money and influence the behavior of the car, but more on that later. For now, it’s a pure educational program, so that later we can understand each other well.

So, 195/65R15. Classic case. Let's squat down next to our car. The first number is the width of the running part of the tire, roughly speaking, the tread width. Expressed in millimeters. That is 195 mm. - this is the width of your wheel. Most people have no problems understanding this figure.

Through the fraction 65 is the profile size. Expressed as a percentage of the width. Not in millimeters! The profile is the part of the tire that “sticks out above the rim.” Sidewall. That is, the height of this sidewall will be 195x65% = 125.75 mm. Not 65 mm. And not anything else. Moreover, from this diagram it clearly follows that the height of 65% with a width of 195 will be one, but if the tire is marked (conditionally) 225/65R15, it will be completely different! 225x65%=146.25 mm. Although the numbers 65 are the same!

R is the radial design of the tire, or more precisely, the way the metal cord is laid inside it. Once upon a time, the tire design involved diagonal laying, but that was a long time ago. Nowadays you almost never see “bias” tires, they are all radial, and the letter R will not tell anyone anything new, it will only cause controversy about the notorious radius...

And finally, the number 15. This is the diameter. The diameter of the tire seat, the inner diameter, the part that comes into contact with the disc. Expressed in inches. 1 inch = 2.54 cm. That is, 15x2.54 = 38.1 cm This is also the outer diameter of the disk, if anyone hasn’t guessed...

Which tires can be installed and which cannot?

And then the fun begins. We can play with these numbers if we want to put other tires (rims) on the car. Ideally, the main thing is that the overall diameter does not differ, or differs slightly. Example.

The 195/65R15 wheel has this overall diameter: 38.1 cm - inside, plus 125.75 mm x2 = 251.5 mm (there is a profile at both the top and bottom). Let's convert to centimeters for simplicity, it turns out 38.1 cm + 25.15 cm = 63.25 cm. That's how it is! This is the total diameter of the wheel.

Now, if you want to install other wheels, the car owner must understand the following: automakers understand this figure the same way as we do. Taking into account the wheel diameter, the suspension is designed, braking system and body. Therefore, for the same car model (for example, for a Volkswagen Polo sedan), three wheel sizes are officially allowed. The simplest version is content with 175/70R14 (total diameter 60.06 cm), 185/60R15 (60.3 cm) and 195/55R15 (59.55 cm).

It turns out that the “14 wheel” is BIGGER, albeit slightly, than the 15 wheel in the case of 195/55. This is related to the question raised above, about installing bigger wheels for the winter... You need to carefully calculate everything. Will a larger diameter number mean a larger wheel size overall? Not always.