Sometimes some novice car owners are faced with the need to replace a disk - one or more, and this task turns out to be more difficult than it looks from the outside. And no wonder: 4 * 108, 6J, ET47, Dia 63.3, R15 - what is all this ?! Let's figure it out together.

WHAT SHOULD YOU DO BEFORE YOU BUY THE DISCS?

Choosing the right rims for an existing car, along the way, sorting out all the necessary parameters.

2. WHAT DISC PARAMETERS SHOULD I CONSIDER WHEN PURCHASING?

Regardless of what kind of car you have, when choosing new wheels, you need to consider the following parameters:

• disk type;
• mounting (or landing) diameter;
• number and diameter of mounting holes (PCD);
• disk width;
• disc offset (ET);
• diameter of the central (hub) hole;
• the shape of the mounting holes;
• the presence of humps.

Let's make a reservation right away: if by this moment you have no desire to deal with all these parameters, when choosing discs, simply use the car selection service in large online stores. There you can, simply by specifying the model of your machine, get disks that are guaranteed to suit it in all respects. Well, if the determination to find out everything is still with you, then let's get started.

DISC TYPE - WHAT THEY ARE

All discs are generally divided into three types according to the type of manufacture: stamped, cast and forged. The question of choosing a particular type is a topic for a separate material, but here we will present the main differences.

Stamped rims are the cheapest: these are the same wheels you see on the base trim of budget cars, and they are usually covered with plastic decorative caps. They are made of steel and painted with enamel. Among their advantages, in addition to the lowest price, is high maintainability. The fact is that stamped discs do not break upon impact, but crumple, and subsequently they can be easily repaired. The main disadvantage of such wheels is their high weight and lack of design: this is a purely functional product.

Alloy wheels compete with stamped ones in popularity. Such discs are not made of steel, but of a lighter alloy - usually aluminum. Thanks to the manufacturing technology, alloy wheels can have a wide variety of shapes, which, combined with a lighter weight than the “stamps”, ensures their popularity. Among the disadvantages of such wheels, one can mention a higher price and lower maintainability: alloy wheels do not crumple, but crack when hit hard. Of course, the technology of welding repair and rolling has long been mastered, but it is impossible to guarantee the preservation of the original properties after repair.

Forged wheels are the highest quality and most expensive option. They are produced by hot die forging, which provides the best internal structure of the metal and, accordingly, the highest strength with the lowest weight. The downside of this method is the low prevalence of products and the high price.

In addition to the above three types, there are also so-called prefabricated disks - but this is already exotic, and we will not touch on them. In general, for the average car owner, the choice is between inexpensive but boring stamped wheels and more expensive and beautiful alloy wheels.

MOUNTING (LANDING) DIAMETER

This is quite an obvious parameter: the diameter of the circumference of the disk in inches. As a rule, it is denoted by the letter R: that is, the R17 disc has a diameter of 17 inches.

We note in particular: the letter R itself does not refer to the diameter and came from the parameters of the tires, where it is also mistakenly used in the meaning of "radius", in reality, implying the tire's landing diameter. In the case of the R tire, this is the marking of the radial construction of the cord, but for the disc, this marking is actually not relevant. However, the erroneous "radius" in the meaning of "diameter" and the accompanying R are so ingrained in speech that most sellers and services for selecting discs are already used by default.

The allowable rim diameters for your vehicle are listed in the owner's manuals and on stickers in the doorways - along with recommended tire pressures. When buying tires, it is worth remembering that their landing diameter must match the diameter of the disks.

It is not recommended to exceed the maximum diameter specified by the manufacturer: too large discs, in addition to potential geometric incompatibility, change the parameters of the suspension, affecting the wear of the chassis. In addition, the larger the disc and the lower the rubber profile, the less comfort promises movement on bad roads. However, changes in diameter within the limits specified in the manual, and even an inch over, as a rule, pass without significant consequences.

NUMBER AND DIAMETER OF MOUNTING HOLES (PCD)

This is the so-called “bolt pattern”: the number of holes and the diameter of the circle on which they are located (by the way, the English PCD is just the diameter of the circle, “Pitch Circle Diameter”). The number of mounting bolts can be different and increases with the growth of the mass and speed of the car: usually there are 4-6 of them, but it can be more or less (minimum 3). Most VAZ cars have a 4x98 bolt pattern, with the exception of Oka (3x98) and Niva (5x139.7), as well as new models like Largus (4x100).

Disc bolt pattern must be observed: despite the fact that some discs - for example, 4x98 and 4x100 - seem to be interchangeable, they are not. A seemingly insignificant 2 mm difference in the diameter of the circle on which the mounting holes lie will greatly affect the installation: only one of the four fasteners will be correctly tightened, and the rest will be offset from the center, causing the wheel to beat. In part, the problem can be solved by using bolts with a “floating cone” (more on them below), but in general, the use of discs with inappropriate bolt patterns should be avoided.

DISC WIDTH

This parameter is as simple as the diameter: it is the width of the wheel in inches. Usually in the parameter list it is denoted by the letter J: for example, 5.5J is a five and a half inch wide disc.

The width of the disc, as a rule, is indicated in the same places as the allowable bore diameter, along with it. In addition to the geometric parameters for a car, the width of the disk is also important when choosing tires: the tire is designed to be used with a disk of a certain width, but with some allowable error.

DISC OUTLET

Disc overhang is the distance from the mating plane of the disc attachment to the hub to the longitudinal axis of symmetry of the disc. Let's put it simply: the central axis of symmetry is the line dividing the disk in half along the width described above, and the mating plane is the point where the disk comes into contact with the hub and is screwed to it.

The offset can be positive, zero and negative: if the axis of symmetry lies closer to the car than the attachment plane, then the offset is positive, if they are on the same axis, then the offset is zero, and if the axis of symmetry is more distant from the car than the attachment plane, then it is positive . In other words, the longer the overhang, the deeper the disc sits in the wheel arch, and the smaller it is, the more the disc protrudes outward.

Departure - quite important parameter: it also directly affects the operation of the suspension and wheel bearings. Incorrect offset not only increases or decreases the track, but can also cause accelerated wear on the undercarriage and bearings.

DIAMETER OF THE CENTRAL (HUB) HOLE

The diameter of the central hole is a parameter that does not need additional explanation. It is usually referred to as "Dia", "DIA" or "D" in the list of disk specifications. This is also an extremely important indicator: if the central hole of the disc is smaller than required, the disc simply cannot be installed, and if it is larger, then centering rings will be required to center the disc on the hub.

Many people mistakenly believe that when installed, a disk with a too large center hole will center itself on the hub due to the tightening of the bolts, but this is not the case. Accordingly, the beating and vibration that do not disappear after balancing the wheels is a reason to check the coincidence of the diameters of the central hole of the disk and the hub and, if necessary, the presence of centering rings.

SHAPE OF MOUNTING HOLES

The shape of the mounting holes is important in terms of the type of bolts or nuts that will be attached to the disc. As a rule, bolts and nuts for stamped discs have only a slightly conical shape of the plane adjacent to the disc when tightened, and the bolts are also noticeably shorter. How to legalize SUV tuning?

The latter is related to the minimum thickness of the stamped disk. A cast disc is noticeably thicker than a stamped one, and in addition, its mounting hole has a more pronounced conical shape, which requires the use of other fasteners. In addition to the conical, the seat of the mounting hole of some disks can be designed for the use of fasteners with a hemispherical and flat working part.

And one more thing: there are bolts with the so-called "floating cone": they allow you to partially compensate for the slight discrepancy between the PCD disc and the required parameters. The working conical part of such bolts is made in the form of a separate ring, put on the bolt, and is displaced relative to the longitudinal axis of the bolt when tightened.

AVAILABILITY OF HUMPS

Humps are protrusions on the outer surface of the disc that fix the tubeless tire to the disc. Remember the pops that are heard when the tire changer inflates the tire after mounting on the rim? This is the moment of “landing” of the tire: the bead ring of the tire sits between the hump and the rim of the disk. In fact, this indicator is listed last in our material, because at present it is practically irrelevant: almost all modern disks are designed for tubeless tires and have humps.

However, if, for example, you decide to purchase retro discs of respectable age, please note that they may well be designed to install exclusively tube tires without humps. However, tubeless tires can be installed on them, however, the issue of its tight fit, as well as driving safety, will remain open: with insufficient tire pressure, the risk of “taking off your shoes” in a turn will be very high.

Selection of wheels for the car

Almost every car disk has its marking. If it is available on the disk, then it will not be difficult to sort out all the necessary information that will determine the degree of its compliance with a particular car. However, before self-selection of car wheels, it is recommended that you read the car's operating manual. It will definitely contain the parameters required and recommended by the vehicle manufacturer.

Size D(measured in inches) - the diameter of the annular part of the rim on which the tire rests. It is also called " landing diameter».

Size IN(measured in inches) - the distance between the inner surfaces of the bead flanges of the wheel. The possible width of the profile of the installed tires directly depends on it. Permissible is the deviation in 0,5-1 inch, but for low profile tires, this deviation should be minimal.

ET(measured in millimeters) - the distance from the plane of the disc, which is adjacent to the hub, to the plane that passes through the axis of the middle of the width of the disc rim. This parameter determines how deep the disk is recessed into the car arch. It is also called " departure (removal) of the disk". Permissible deviation is up to 5 mm. With large deviations, it is necessary to try on the discs, since it is possible that the disc will rest against the fender liner, suspension parts or elements of the vehicle's brake system. In addition, the installation of wheels with a reach less than that provided will lead to a significant decrease in vehicle stability, increased steering sensitivity and uneven distribution of braking forces.

PCD(measured pcs/mm) - means the number of holes for fasteners / the diameter of the circle of the centers of the holes. It is this size of the rim that must absolutely correspond to the values ​​​​declared by the car manufacturer. If it is changed, it will not be possible to securely fix the wheel on the vehicle hub. Even deviation in 1 mm will lead to misalignment of the wheels and disc mounting parts.

HUMP(measured in millimeters) - the distance between the annular protrusions, which serve to additionally fix the beads of tubeless tires during installation.

DIA(measured in millimeters) - the diameter of the central hole. Its value must correspond to the diameter of the centering protrusion located on the vehicle hub. Diameter deviation is allowed only in the direction of increase. In this case, it is necessary to install special adapter centering rings. Some domestic "craftsmen" manage to install alloy wheels on cars with a DIA value less than the standard one, by reaming the central hole of the disk. However, such modernization can lead to negative consequences due to changes in the structure of the disk metal.

By the way! You can choose wheels for your car in our catalog.

Right size

Size: "width-rim"

This ratio includes two parameters - rim width And mounting diameter. The vast majority of modern passenger cars are equipped with 13-, 14-, 15-, 16-, 17-inch wheels. Recently, there has been a tendency to increase the mounting diameter. Cars that have 13-inch wheels as standard are often fitted with 14- and even 15-inch wheels. This trend is explained by the desire of car owners to use tires of low and ultra-low series, since their driving characteristics are better than those of high-profile tires. But with a constant wheel diameter, the lower the tire profile, the more metal in the wheel, and, accordingly, less rubber. The use of steel rims with an increased mounting diameter is impractical, because this increases the total mass of the wheel, but the use of light alloy rims will increase the mounting diameter without making the wheel heavier. Larger brake elements are installed on sports versions of production cars, therefore the discs must also be larger than the mounting diameter, since the parts of the brake system will abut against the disc rim.

Rim width

There is a golden rule for choosing a rim width - it should be 25% smaller than the width of the tire profile. Example: to select the width of the disk for the tire size 185/60 R14 it is necessary to convert the width of the tire profile from millimeters to inches. To do this, you need to divide 185 by 25.4 (the number of millimeters in one inch). In inches it will turn out - 7.68. From this value it is necessary to subtract 25% and round the resulting number to the standard value.

Those. the conversion formula will look like this: 185/25,4-25%=5,46 . Thus, for a tire size 185/60 R14, it is necessary to use a disk with a width 5,5 inches. The permissible deviation of the disc width from the standard is 0,5-1 inch for rims up to 15" in diameter and 1-1,5 for rims over 15 inches in diameter.

Of course, it is best to choose a disk exactly under the tire. The use of both too narrow and too wide rims is undesirable, since this violates the design profile of the tire. Its sidewalls are either compressed by the edges of the rim, or stretched on it. As a result, the driving characteristics of the tire are violated - its lateral rigidity, the resistance to withdrawal are reduced, the response to a turn worsens, etc. Also, changing the size and shape of the tire contact patch with the road surface significantly increases the risk of hydroplaning, which in rainy weather can lead to serious consequences.

Size: "Car-wheel"

PCD

As already mentioned, it is necessary to use on a particular car model only those wheels whose PCD value is determined by the vehicle manufacturer. For example, a car hub with a PCD of 4x98 is often fitted with discs with a PCD value of 4x100. It seems that a difference of only 2 mm should be completely insignificant, however, in this case, only one bolt (or nut) out of four will be fully tightened. The rest of the holes will lose alignment and the fasteners will either not hold out, or will be tightened skewed, since the disc will not fit completely on the hub. And on the go, such a wheel will vibrate strongly and, in addition, tightened threaded elements will spontaneously unscrew.

DIA

As a rule, regular car wheels have a central hole that is precisely fitted to the hub axis. At the factories of manufacturers, the wheels are centered precisely on this hole - its diameter is called " boarding". But when buying discs in a store, it often turns out that the central hole of the disc is somewhat larger than the standard one. This should not be surprising - most manufacturers make discs with a central hole of a deliberately increased diameter and complete the disc with a set of adapter rings. This allows you to install it on various car models. In this case, the wheels are centered on the PCD value.

Wheel offset (ET)

There are three types of wheel offset - null, positive(the disc hub protrudes outward relative to the middle axis of the rim) and negative(the disc hub is recessed inward relative to the middle axis of the rim). Each car model has a standard disc offset value. This ensures optimal handling and vehicle stability, as well as the lowest load on the wheel bearings. German automakers designate departure as " ET”, French - as “ deport", English-speaking manufacturers - as " offset". Installation of wheels with an abnormal offset of the disc is undesirable, since a decrease in the offset sharply increases the load on the hub bearings and the suspension as a whole, and an increase leads to unwanted friction of the disc against the elements of the suspension or brake system.

Disc marking examples

6x15 ET35 5x100 D57.1, where:

• 6 - wheel width in inches;
• 15 - disc diameter in inches;
• ET35- disk offset in millimeters;
• 5x100- the disc has five mounting holes with a diameter of the circle of the centers of the holes of 100 mm;
• D57.1- the disc has a central hole with a diameter of 57.1 mm.

Wheels and tires are one of the most important elements of a modern car, providing not only driving comfort, but also safety, and therefore the choice of tires and wheels must be taken seriously. To make this task easier for you, we have put together all the rules and nuances associated with the selection of wheels and tires, as well as the subtleties of their various combinations.

Let's start with the simplest. If you are going to buy new wheels and tires, be sure to look at your car's owner's manual, in which the manufacturer, as a rule, always indicates the necessary information about the allowable sizes of wheels and tires. It is categorically not recommended to deviate from factory recommendations, especially for novice motorists, since discs and tires that do not correspond to the correct sizes, at least, can lead to faster wear of the suspension and the wheels themselves, and, at the maximum, can provoke a sharp deterioration in the driving performance of the car, which is fraught with an increase in fuel consumption, a decrease in controllability and even an accident on the road.

Before choosing wheels and tires, you need to understand their markings. Wheels are usually labeled something like "R13 4×98 ET35 J5 D58.6", where R13 is the diameter of the rim in inches, 4×98 is the number of mounting holes and the diameter of their centers in millimeters, ET35 is the wheel offset or distance from the plane of symmetry of the rim to the plane of the mounting of the disc (mm), J5 is the width of the disc rim in inches, and D58.6 is the diameter of the central hub hole. In turn, tires have the main marking of the type “235/70 R16 105H”, where R16 is the diameter of the rim for which the rubber is intended, 235 is the width of the tire (profile) in millimeters, 70 is the percentage ratio of the tire width and the height of its profile (series), and 105H - indices of permissible load and speed.

• When selecting new wheels, first of all, you should pay attention to the diameter of the rim, which must correspond to the inner (landing) diameter of the tire. That is, if you buy R14 wheels, then the rubber, respectively, should also have a diameter of 14 inches.
• Do not forget that the permissible load index and the permissible speed index of the tires you have chosen must fully comply with the characteristics of your car, which can be found in the owner's manual.
• Next, it is necessary to take into account the ratio of the width of the rim and the width of the tire profile, while the width of the rim of the rim should be about 70 - 75% of the width of the selected rubber, since it is at this ratio that the correct fit of the tires on the disks is ensured, guaranteeing the calculated driving performance. The problem is in this case is that the width of the rim is indicated by manufacturers in inches, and the width of the tire profile in millimeters, so you have to use a calculator and convert millimeters to inches using a special formula. For example, your choice fell on tires 195/70 R15. Divide 195mm by a factor of 25.4, resulting in a width of 7.68 inches. Next, reduce this value by 30% and get 5.38 inches. Now it remains only to round the resulting value to the nearest standard size and you get the desired rim width, ideal for the selected rubber, in this case 5.5 inches.
• The fourth point is the correct selection of the wheel offset, which can be negative (the hub is recessed), positive (the hub sticks out to the outer part of the disk) or zero (the hub is located strictly in the middle of the disk). In this case, you should strictly follow the recommendations of the car manufacturer, since the offset is calculated in order to minimize the load on the wheel bearings and other suspension components, and any deviation from the norm, even by small amounts, can lead to rapid wear of the suspension elements, loss of vehicle stability and controllability.
• And finally, the last point is the selection of fasteners. If you buy standard wheels for your car, then there should be no problems with this item. But, for example, in the case of changing stamped wheels to alloy wheels, the length of the old mounting studs may not be enough, so you will have to purchase a new set.

Now let's talk about different combinations rims and car tires. Let's start with the standard, i.e. optimal sizes recommended by the manufacturer or simply used as basic ones for the corresponding equipment of your car. In this case, the closest correspondence of all driving characteristics to factory engineering calculations is ensured, which will ensure a balanced behavior of the car in all respects (dynamics, braking, handling, comfort, etc.).

However, each automaker allows the deviation of the permitted sizes of rims and tires up or down, which is indicated in the instruction manual. If you choose the minimum size of the rims, then it becomes possible to install tires with a higher profile, which can help improve the car's behavior on bad roads and extend the life of both the wheels themselves and the suspension. At the same time, there are also disadvantages - deterioration in grip, reduced controllability and loss of power.

In the opposite situation, when choosing the largest permitted size of rims, it is possible to use low-profile rubber, which improves the dynamic characteristics of the car, as well as increases its directional stability. True, it is worth noting that low-profile tires are very demanding on the quality of the roadway, reduce driving comfort and are prone to aquaplaning.

Quite often, motorists tend to put on their car the widest possible tires, usually low-profile. But this is justified only for powerful cars that involve a sporty driving style. If you are the owner of a compact or mid-size car with a low-power engine, then much the best choice there will be narrow tires, since it is impossible to evaluate all the advantages of wide tires on low-power cars, but all the disadvantages inherent in them will manifest themselves in full. Returning to wide wheels, we add that you should not use rubber whose profile width exceeds the dimensions allowed by the car manufacturer, as this entails the removal of all insurance obligations in the event of an accident. However, even without this, too wide tires will not allow you to fully drive the car, because during maneuvers (especially when the car is fully loaded), the sides of the tires can touch the arches, which is fraught with a decrease in handling and rapid wear of rubber.

The last thing we would like to talk about is the static diameter of the wheel, i.e. the full diameter of the rim, together with the tire seated on it, inflated to working pressure. When changing discs of one diameter to a larger one, it is sometimes difficult to find a rubber that allows you to maintain the factory static wheel diameter that best suits your car. In this case, manufacturers are allowed to increase the static diameter, but it must be remembered that this leads to a change in driving characteristics and may adversely affect the operation of modern electronic assistance systems, which are equipped with a large number of cars now produced. We also note that it is not recommended to increase the static diameter of the wheel by more than 3 cm, since a further increase leads to a noticeable deterioration in the traction characteristics of the car and to increased fuel consumption.

When the first joyful sensations from buying a car pass, when driving it becomes your daily work, it is at this moment that you face questions that you never thought about before. For example, how to choose the right wheels for your car, and specifically - car wheels.

Currently, the market represents a huge selection of car discs. Therefore, which disks and how to choose the right one sometimes becomes an insoluble task.

What discs are made?

There are several varieties: stamped, cast and forged wheels.

Stamped discs are the most common. They are made of ordinary steel, painted with enamel, usually in black or dark gray. The main advantage is that they are easy to repair. Always, with the ability, with the help of a simple tool, it is possible to return the shape of the disk. Of the minuses - they do not differ in the elegance of forms. You must have a set of stamped wheels, usually used with winter tires.

Alloy wheels are made from lightweight alloys, usually aluminum.

They have a different shape, and are lighter than stamped discs. This explains their popularity among experienced motorists. However, the high cost and, in practice, the impossibility of repair are a minus of this variety. We recommend that you buy if you are sure of careful driving and attentiveness on the road. And best used with summer tires.

How to choose an alloy wheel for a car?

The main alloys used in alloy wheels are aluminum, titanium, magnesium. Aluminum rims are light, strong and virtually corrosion resistant. Therefore, they are the most recommended for daily use. Magnesium alloy wheels are very susceptible to corrosion, so it is recommended to use them in warm and dry conditions, or permanently cover with an anti-corrosion coating. Titanium wheels belong to the elite group, so if you have a prestigious car or a sports car, and you plan to drive only in the city, choose titanium wheels.

Which is better - stamped or cast wheel? (video)

The next variety is forged wheels.

forged disc

The best and highest quality, but also the most expensive type. Made by hot stamping, they have high strength and low weight. Of the minuses - with a strong impact on an obstacle, it retains its shape, but there is a possibility of destruction of the wheel or cord, which leads to a complete replacement of the tire.

How to choose car wheels (video)

How to choose wheels on a car by size?

Usually, all information about the sizes of wheels and disks is indicated in the instructions for your car. Additionally (depending on the car) it can be indicated on separate parts, for example, on the gas tank cap.

Departure size;

Hub hole diameter size;

The size of the landing diameter;

Disc mount;

The shape of the holes for fasteners;

Information on disks (video)

Inches are the classic measure of wheel width. The value is marked as "J". For example, 5.5J. Stands for 5.5 inches wide. Tires are also marked in inches, each tire has its own rim.

Departure affects the functionality of the auto suspension in general, and bearings in particular. Incorrect departure will lead to premature wear of the chassis. Concepts such as positive overhang, negative overhang and zero overhang are used.

Departure calculation (video).

The hub hole is where the disc is screwed onto the hub of the car. Therefore, it must fit exactly. If the hole is small, the disk will not install. With a large hole, balancing with rings will be required.

Disc seat diameter. This is the disc diameter in inches. Marked with the letter R.

For example, R18 indicates an 18" disc.

We remind you that the required disc diameters for your car are indicated in the book for the operation of your car.

REMEMBER! The tire diameter must match the diameter of the rims.

location diameter.

Number of fixing holes.

In English - PCD (PITCH CIRCLE DIAMETER). In Russian - "razboltovka".

The number of mounting bolts can vary from four to six on average. Minimum 3. This is important and must be strictly observed.

The shape of the holes for fastening discs.

Forged disc bolts are slightly tapered. The length is shorter than others. In cast, the conical shape is more pronounced, here you need longer fasteners. Some designs use flat and hemispherical fasteners.

Humps.

Outside the disc there are protrusions that fix the tubeless rubber. They are called humps. They are present on every disc. With the exception of discs for pneumatic chambers.

Interesting fact.

For more than 100 years, pneumatic tires have been installed on cars, which are inflated with atmospheric air. Internal chamber pressure ensures structural rigidity and ease of movement. Until the 80s of the last century, a rubber or rubber chamber was located inside the tire. But, starting from the 2000s, tubeless tires came to replace chambered tires. Today, almost all cars, especially new ones, are equipped with tubeless tires.

Disk options.

Almost every car disk has its marking. If it is available on the disk, then it will not be difficult to sort out all the necessary information that will determine the degree of its compliance with a particular car. However, before self-selection of car wheels, it is recommended that you read the car's operating manual. It will definitely contain the parameters required and recommended by the vehicle manufacturer.

Size D(measured in inches) - the diameter of the annular part of the rim on which the tire rests. It is also called "landing diameter".

Size IN(measured in inches) - the distance between the inner surfaces of the bead flanges of the wheel. The possible width of the profile of the installed tires directly depends on it. A tolerance of 0.5 - 1 inch is acceptable, but for low profile tires, this deviation should be minimal.

ET(measured in millimeters) - the distance from the plane of the disc, which is adjacent to the hub, to the plane that passes through the axis of the middle of the width of the disc rim. This parameter determines how deep the disk is recessed into the car arch. It is also called "disc overhang". A deviation of up to 5 mm is permissible. With large deviations, it is obligatory to try on the disks, since it is possible that the disk will rest against the fender liner, suspension parts or elements of the vehicle's brake system. In addition, the installation of wheels with an offset less than that provided will lead to a significant decrease in vehicle stability, increased steering sensitivity and uneven distribution of braking forces.

PCD(measured pcs/mm) - means the number of holes for fasteners / the diameter of the circle of the centers of the holes. It is this size of the rim that must absolutely correspond to the values ​​declared by the car manufacturer. If it is changed, it will not be possible to securely fix the wheel on the vehicle hub. Even a deviation of 1 mm will lead to misalignment of the wheels and fasteners.

HUMP(measured in millimeters) - the distance between the annular protrusions, which serve to additionally fix the beads of tubeless tires during installation.

DIA(measured in millimeters) - the diameter of the central hole. Its value must correspond to the diameter of the centering protrusion located on the vehicle hub. Diameter deviation is allowed only in the direction of increase. In this case, it is necessary to install special adapter centering rings. Some domestic "craftsmen" manage to install alloy wheels on cars with a DIA value less than the standard one, by reaming the central hole of the disk. However, such modernization can lead to negative consequences due to changes in the structure of the disk metal.

Right size.

Size: "width-rim"

This ratio includes two parameters - the width of the rim and the mounting diameter. The vast majority of modern passenger cars are equipped with 13-, 14-, 15-, 16-, 17-inch wheels. Recently, there has been a tendency to increase the mounting diameter. Cars that have 13-inch wheels as standard are often fitted with 14- and even 15-inch wheels. This trend is explained by the desire of car owners to use tires of low and ultra-low series, since their driving characteristics are better than those of high-profile tires. But with a constant wheel diameter, the lower the tire profile, the more metal in the wheel, and, accordingly, less rubber. The use of steel rims with an increased mounting diameter is impractical, because this increases the total mass of the wheel, but the use of light alloy rims will increase the mounting diameter without making the wheel heavier. Larger brake elements are installed on sports versions of production cars, therefore the discs must also be larger than the mounting diameter, since the parts of the brake system will abut against the disc rim.

Rim width.

There is a golden rule for choosing a rim width - it should be 25% smaller than the width of the tire profile. Example: to select a rim width for a 185/60 R14 tire, you need to convert the tire profile width from millimeters to inches. To do this, you need to divide 185 by 25.4 (the number of millimeters in one inch). In inches, it will turn out - 7.68. From this value it is necessary to subtract 25% and round the resulting number to the standard value.

Those. the conversion formula will look like this: 185 / 25.4 - 25% \u003d 5.46. Thus, for a 185/60 R14 tire, a 5.5-inch wide wheel should be used. The allowable disc width deviation from the standard is 0.5-1 inch for discs with a diameter of up to 15 inches and 1-1.5 inches for discs with a diameter of more than 15 inches

Of course, it is best to choose a disk exactly under the tire. The use of both too narrow and too wide rims is undesirable, since this violates the design profile of the tire. Its sidewalls are either compressed by the edges of the rim, or stretched on it. As a result, the driving characteristics of the tire are violated - its lateral rigidity, the resistance to withdrawal are reduced, the reaction to a turn worsens, etc. Also, changing the size and shape of the tire contact patch with the road surface significantly increases the risk of hydroplaning, which in rainy weather can lead to serious consequences.

Size: "Car-wheel."

PCD.

As already mentioned, it is necessary to use on a particular car model only those wheels whose PCD value is determined by the vehicle manufacturer. For example, a car hub with a PCD of 4x98 is often fitted with discs with a PCD value of 4x100. It seems that a difference of only 2 mm should be completely insignificant, however, in this case, only one bolt (or nut) out of four will be fully tightened. The rest of the holes will lose alignment and the fasteners will either be undertightened or tightened skewed, since the disc will not fit completely on the hub. And on the go, such a wheel will vibrate strongly and, in addition, tightened threaded elements will spontaneously unscrew.

DIA.

As a rule, regular car wheels have a central hole that is precisely fitted to the hub axis. At the factories of manufacturers, the wheels are centered precisely on this hole - its diameter is called the “landing” one. But when buying discs in a store, it often turns out that the central hole of the disc is somewhat larger than the standard one. This should not be surprising - most manufacturers make discs with a central hole of a deliberately increased diameter and complete the disc with a set of adapter rings. This allows you to install it on various car models. In this case, the wheels are centered on the PCD value.

Departure of a wheel. (ET)

There are three types of wheel offset - zero, positive (the disc hub protrudes outward relative to the middle axis of the rim) and negative (the disc hub is recessed inward relative to the middle axis of the rim). Each car model has a standard disc offset value. This ensures optimal handling and vehicle stability, as well as the lowest load on the wheel bearings. German automakers designate offset as "ET", French as "Deport", English-speaking manufacturers as "Offset". Installation of wheels with an abnormal offset of the disc is undesirable, since a decrease in the offset sharply increases the load on the hub bearings and the suspension as a whole, and an increase leads to unwanted friction of the disc against the elements of the suspension or brake system.

Marking examples.

6x15 ET35 5x100 D57.1, where:

6 - wheel width in inches;

15 - disc diameter in inches;

ET35– disc overhang in millimeters;

5x100- the disc has five mounting holes with a diameter of the circle of the centers of the holes of 100 mm;

D57.1– the disc has a central hole with a diameter of 57.1 mm.