Since the appearance of the first cars, their owners have been faced with the problem of wheel balancing. Previously, the speed and quality of roads were not high, so balancing problems worried few people. Over time, everything has changed dramatically.
Wheel imbalance refers to the presence of unbalanced rotating masses - hubs, brake drums, etc. Due to imbalance, vehicle control becomes significantly more difficult, the service life of shock absorbers, suspension, steering wheel and traffic safety in general are reduced. All this, therefore, increases technical costs. car maintenance.
Since the wheel is a rotating object of any car, it must have a symmetrical shape. Each point of rotation of the wheel must be equidistant from the axis of rotation. The center of gravity of the wheel must be on this very axis.
Wheel balancing refers to the process of reducing to an acceptable level the imbalance of the wheel, hub and disk, wheel mounting and suspension elements.
The reasons for imbalance are: tire wear, disc deformation and other reasons that disrupt the shape of the wheel.
A wheel can be called correctly balanced if its axis of rotation coincides with the main central axis of inertia. When manufacturing wheels and rubber, certain errors from the nominal values are allowed. For this reason, any wheel is not balanced initially.
There are two types of wheel imbalance - static and dynamic.
With static imbalance, the main axis of inertia (O1-O1) is parallel to the axis of rotation (O-O), but does not coincide with it.
Wheel imbalance can be:
- static;
- dynamic.
When static imbalance, the severity of the unbalanced mass (mH) creates a torque. That is, a freely rotating wheel will move until the unbalanced mass reaches its lowest position. In this case, the movement of the wheel will be similar to a pendulum.
In order to eliminate static imbalance, it is necessary to strengthen the balancing weight (my) in a place opposite to the location of the unbalanced mass. This is called static wheel balancing.
Dynamic imbalance is expressed in the imbalance of the wheel along its width. It is only noticeable when it is rotated. In this case, the axis of rotation passing through the center of gravity does not coincide with the main central axis of inertia. As a result, a certain angle α is formed between the axes.
Two masses (mH) lying in the center plane must be reduced to the unbalanced masses of the wheel. When such a wheel rotates, centrifugal forces (Pc) arise, acting in opposite directions, creating two forces with a torque of rotation M=P α. The resulting value is a characteristic of the magnitude of the dynamic imbalance.
In order to eliminate dynamic imbalance, it is necessary to attach balancing weights (my) to the edges of the rim, at the point of action of these forces, on the inside and on the front of the disc. Dynamic balancing must be carried out on a special machine.
Wheel imbalance can be caused by its design features (presence of a valve hole in the disk, tire tread pattern, etc.) or manufacturing technology (wheel shape errors, material heterogeneity, etc.).
Radial and lateral runout, ovality and shape deviations- main assessments of the accuracy of wheel manufacturing. Balance is affected only by runout; ovality has virtually no effect.
Radial runout (RPO) is the difference in distances from various points on the tire tread to the wheel's axis of rotation. In other words, this is the deviation of the tire's roundness from an ideal circle. Lateral (transverse) runout is the difference in the distance of the lateral surface, per one revolution of the wheel relative to the surface perpendicular to the axis of rotation of the wheel.
As is already known, imbalance and beats occur due to the quality of production of the unbalanced, rotating masses of the machine. It is almost impossible to create a perfect wheel. Therefore, in the manufacture of wheel assembly parts and tires, certain tolerances and standards are established. The tire is the most important cause of wheel imbalance, since it is the most distant from the center of rotation, and has a large mass, a complex structure and is made of materials of different compositions: rubber, fabrics and steel wires, etc. The effect on imbalance increases as the mass of the tire materials moves away from the center of the wheel.
General imbalance of tube tires consists of imbalances in the tire and the ride tube. In the chamber itself, the balance of the wheel is affected by the difference in the thickness of the chamber walls, joints and valves. Therefore, to improve balance, the valve is installed on the opposite side of the joint. The tube is installed so that the valve coincides with the lightest part of the tire. However, the amount of tube imbalance is significantly less than the tire imbalance.
The main reasons that influence the amount of imbalance and runout of tires are:
Tread joint. Heterogeneity of its thickness along the length of the wheel, variable tread pattern, the presence of studs, for winter tires;
- joints of cord layers in the frame and breaker;
- joint of the sealing layer for tubeless tires;
- strong overlap of wire in the bead ring;
- the difference in the angles of inclination of the cord threads in the frame and breaker;
- divergence of cord threads in the tire layers;
- accuracy of mold production;
- different thickness of the side walls;
- markings on the sidewall of the tire, which are applied to one place, etc.
Most of the named factors influencing balance do not manifest themselves outwardly. They relate to the internal causes of imbalance. Reasons that can be seen with the naked eye.
An indispensable condition for improving the quality of produced wheels is tightening the requirements for production technology. All these measures should ultimately lead to a reduction in imbalance and beats.
As mentioned above, it is impossible to make a perfect wheel. Therefore, the existing state standard 4754-97 establishes requirements for imbalance indicators.
Proper balancing improves ride comfort. But the main thing is not even convenience. Wheel imbalance creates shock loads on the hub and bearings. And this load is not light! The imbalance is only 20 grams. on a 14-inch wheel, at a speed of 100 km/h, creates a load equal to the blows of a three-kilogram sledgehammer with a frequency of 800 blows per minute.
The problem of wheel balancing arose with the advent of the first cars. At low speeds and bad roads it remained virtually invisible. The situation has changed dramatically over time. Therefore, its relevance has increased sharply.
Drivers often observe signs of wheel imbalance. As a result, the steering wheel wobbles. Wheel disc runout caused by displacement of its landing flanges during rotation. The displacement can be twofold: parallel to the radius or axis of rotation of the disk. In the first case, radial runout occurs, in the second, axial runout.
Wheel runout can be checked using a special indicator. It is pressed against the surface of the rotating wheel. The device records the wheel displacement in the radial or axial direction. Readings are taken in millimeters. The amount of wheel runout cannot be assessed visually. The measurement accuracy of the indicator is no less than 0.05 mm.
Wheel radial runout associated with static imbalance. The disc takes on an egg-shaped shape. The wheel oscillates up and down. The rotation of such a wheel is accompanied by the presence of a variable torque on the axle. The result is irreversible damage to suspensions, tires, and steering gear.
Wheel axial runout- the result of the displacement of the disk along the horizon. Experts call this shift the “figure of eight.” The axial displacement of the disk is caused by the uneven distribution of masses in the planes. Negative consequences of this defect:
- rapid tread wear;
- damage to suspensions and steering gear;
- uneven wear of the tire tread, which leads to a reduction in its service life.
Wheel imbalance is caused by the presence of asymmetrical rotating masses. In particular, these could be hubs and brake drums. Since the wheel is a body of rotation, it must be given a symmetrical shape. The balancing procedure consists of reducing wheel imbalance to an acceptable limit.
The balance is disrupted due to tire wear and various disc deformations. There may be other reasons that distort the shape of the wheel. A properly balanced wheel is a condition for safe movement. The central axis of inertia of such a wheel coincides with the axis of its rotation. The manufacturing process of wheels and tires is associated with certain errors. Therefore, the wheel is not initially balanced.
It is customary to distinguish between static and dynamic imbalance. Static imbalance has its own characteristics. The unbalanced mass serves as a source of torque. In other words, the wheel will perform an oscillating motion. It will continue until the unbalanced mass reaches its lowest point. The wheel behaves like a pendulum.
Elimination of static imbalance is carried out by strengthening the balancing load. The attachment point of this load is the point opposite to the unbalanced mass. This is how the wheel is statically balanced.
The cause of dynamic imbalance is imbalance in the width of the wheel. It only appears during its rotation. This leads to a displacement of the axis of inertia and the axis of rotation. The rotation of such a wheel is accompanied by the emergence of centrifugal forces. Elimination of dynamic balance is possible by securing balancing weights. Dynamic balancing is carried out on a special installation.
The reasons causing dynamic imbalance, in particular, include:
- valve hole in the disk;
- wheel shape error;
- the presence of inhomogeneities in the material.
home cause of wheel runout and imbalance - heterogeneity of the tire, because it is located at the greatest distance from the axis of rotation. In addition, it has greater mass and a complex structure. It includes various materials: rubber, fabric, steel wires. The further the particle is from the axis, the stronger the effect on the imbalance.
Runout at speed
Why is this happening? wheel wobble at speed? Let us highlight the three most characteristic modes of vehicle movement:
- at low speed;
- at high speed;
- when braking.
Wheel runout at low speed may be caused by a number of reasons. The main factors include:
- presence of bumps, bulges, irregularities on the tire;
- wear of rubber from the inside;
- various disk damages;
- Wheel not balanced.
Beating at high speeds is a consequence of imbalance. When pieces of dirt stick to the wheel, the balancing is disrupted. This often occurs after driving on a dirt road. Under the influence of adhering snow or ice, the same thing happens. Another reason is also possible. Formation of pellets inside the tire.
Wheel runout when braking perhaps due to:
- unbalanced wheels;
- destroyed bearing;
- behaved brake discs.
Front wheel runout feels stronger. It is unsafe to drive with imbalance. In addition to vibration, tires, wheels, and suspension elements wear out. The car may lose stability, which will lead to an emergency.
Rear wheel runout affects driving stability to a lesser extent. People often ask: “Do the rear wheels need to be balanced?” Necessarily! The imbalance here also leads to uneven tire wear. The consequences of rear wheel runout are no less detrimental. Discs and suspensions deteriorate quickly. Therefore, they cannot be ignored.
Terminology
A wheel assembly is a wheel with a tire mounted on it.
A wheel is a rotating element of a car that transmits torque and absorbs the load from the mass of the car. The wheel is located between the tire and the hub.
A tire is an elastic shell filled with air and designed to be mounted on a rim.
The wheel of a modern passenger car, as a rule, consists of non-separable elements: a disk and a rim.
Wheel disc is a part of the wheel that is the connecting element between the car hub and the wheel rim.
The wheel rim is the part of the wheel on which the tire is mounted and rests. Different sections of the rim have specific names:
Rim flange is the part of the wheel rim that forms the side support for the tire bead.
Rim flange is a part of the rim intended for mounting the base of the tire bead.
Hump is an annular protrusion on the rim that prevents the toe of the tire bead from sliding off the seat under load and depressurization of the tubeless tire.
Mounting groove - a part of the rim that has a width and depth sufficient for mounting and dismounting the tire bead through the bead flange of the rim.
Main elements of the tire:
– protector
– sidewall
– containment layer
To the consumer
1. Make sure that the vibration of the car appears on different types of roads and that this is not associated with ruts and unevenness on the road (road markings, changes in types of road surface, minor unevenness on the road...)
2. Inspect the wheels - clean the wheels from dirt, wash them, especially on the inside. Inspect the wheels for damage. Carefully inspect the tires - remove all stuck objects from the tread pattern: stones and other objects.
3. Check the level of tightening of bolts/nuts or other fastening elements of the wheels, make sure that the tightening force has not weakened.
If necessary, tighten the bolts yourself or contact a tire shop.
4. Inspect the wheels for loss of balancing weights. If you find that the goods have been lost, inform your tire specialist or auto mechanic.
5. Check the tire inflation pressure. The pressure should only be checked and adjusted when the tires are cold (i.e. not immediately after prolonged continuous use) and must comply with the vehicle manufacturer's recommendations (see the factory information badge (sticker, sticker), which is usually located on the gas filler flap or in the driver's door opening doors).
6. If all of the above steps do not eliminate the vibrations, you should contact a tire repair shop. Try to determine which wheel is the source of vibration. Provide this information to a tire specialist or auto mechanic.
8. After tire fitting, exclude sudden starts and emergency braking from your driving style for a period of one week from the date of tire fitting to avoid the tire turning on the wheel.
INFORMATION SHEET:
Vibration in the steering wheel or car can be caused by both tire characteristics and other reasons
Causes of wheel runout
To a specialist
1. Check with the consumer - which wheels are the source of vibration? When are vibrations felt?
2. Check the internal air pressure in all tires.
3. Thoroughly clean the wheel assembly from dust, dirt and other foreign substances
4. Determine which particular wheel assembly is causing the vibration - to do this, evaluate the vibrations with the driver at the current location of the wheels, rearrange the wheels on the car and analyze the changes. As a rule, the cause of vibrations is one, less often two wheels, and not all four. When you have identified the wheel(s), inspect it (them)
4.1 Remove the wheel assembly(s) suspected to be causing the vibrations from the vehicle
4.2 Check the wheel assembly for residual imbalance. The residual imbalance should be no more than 5 grams per side.
4.3 Check the level of radial and lateral runout of all removed wheel assemblies. The level of radial runout should be no more than 1.5 mm (total average value). The runout level should be measured exclusively using a meter on a balancing machine or a dial indicator. Don't use eyeballing.
4.4 Check the quality of tire shrinkage on the rim. Decorative elements of the side zone should be evenly spaced from the edge of the rim.
4.5 Check the condition of the wheels (“discs”) - there should be no damage on the wheels: dents, cracks, traces of welding or repairs.
4.6 Check the condition of the wheel surface in the part where the wheel is adjacent to the vehicle hub (mounting plane) - there should be no traces of corrosion, dirt, varnish, paint or other foreign substances on the mounting surface.
4.7 Check the car hub - the hub must be clean: free of rust, dirt and other foreign substances.
4.8 Check the condition of the central hole of the wheel - it should be smooth, without damage, dirt, corrosion, paint and varnish deposits, as well as other substances. The center hole of the wheel must be exactly the same size as the hub, or the correct size spacers must be used.
4.9 The installed spacer rings for the central hole of the wheel (if any) must match the size of the hole, fit tightly, be clean and must not be damaged.
4.10 If any foreign substances are noticeable on the mating surface, the central hole of the wheel or the vehicle hub, remove them with a brush or other cleaning tools and means.
4.11 Check the condition of the tires - the tires should not show signs of significant repairs, noticeable damage (swells, cuts), foreign objects in the tires (stones, etc.)
4.12 Check fasteners. Nuts/bolts must match: the thread size of the vehicle; by type of mounting surface (cone, sphere, plane) - wheels; along their length, the nuts/bolts must be tightened at least 6 - 8 turns until fully tightened; the thread must be clean, free of dirt, threads must be free of kinks and burrs.
5. When you have determined which wheel assembly is causing the vibrations, make a mark on the tire about the position of the valve and dismantle the tire and inspect:
5.1 Check the condition of the wheel rim - there should be no traces of corrosion, dirt or other foreign substances on the rim (especially on the edge of the rim, the landing shelf, the hump and near it). If there are any substances on the rim, remove them with a brush and/or other means.
5.2 Check the condition of the rim for damage: there should be no dents, cracks, traces of welding or repairs, or geometry corrections. Using a damaged wheel may cause vibrations.
5.3 Measure the runout level of the rim flange. Radial and lateral runout of the wheel rim flange should not exceed 0.5 mm. Runout is measured only by an indicator on a balancing machine or a dial indicator.
5.4 Remove any installed balancing weights and measure wheel imbalance (without tire). Please note that significant wheel imbalance can cause vibration.
5.5 Check the condition of the tires - the tires should not show signs of significant repairs, traces of driving with low pressure, damage to the bead or liner. Using damaged tires may require a large number of balancing weights, cause vibrations and be dangerous!
6. Reinstall the tire onto the rim.
6.1 Before installation, apply a thin, even layer of lubricant specifically designed for installation on the rim and tire. On the rim, the lubricant should completely cover the rim landing flange, the hump, with a thin layer. On a tire, the lubricant should cover both beads of the tire. The lubricant should be applied in a thin layer and should not be applied in excess to prevent the tire from turning on the wheel. Avoid getting grease on the tire sidewall.
6.2 Inflating the tire should be done in two stages. First, inflate the tire without a spool to 4 atmospheres of excess pressure, until the tire is completely seated on the rim, then release the excess pressure, insert the spool and bring the pressure to the required level. Inflating in two stages allows you to better stretch the tire bead and seat it evenly on the seat.
6.3 Attention: when inflating a tire, do not stand on the sidewall of the tire. Always be on the tread side (!)
6.4 Check the quality of tire shrinkage on the rim. Decorative elements of the side zone should be evenly spaced from the edge of the rim. If shrinkage has not occurred completely, dismantle the tire, determine the cause of incomplete shrinkage (incomplete application of lubricant, dirt, rim defects: repairs, jams...), eliminate this cause and re-inflate the tire until complete shrinkage.
7. Remove the wheel assembly from the tire table and tap it on the floor to better seat the bead on the rim. Only after this should the wheel be installed on the balancing machine.
10. Before installing the adhesive weights, according to the type of fastening, bend them and give them the shape of the back side of the rim. The place for installing weights should be additionally cleaned and degreased. Install the weights. After installation, the weights should be further secured with several blows with a hammer.
11. Mark a spot on the tire near the tire inflation valve. If after some time this mark moves relative to the valve, this will indicate that the wheel is turning inside the tire. In this situation, the driver should pay attention to the way he drives the car, and also reduce the amount of lubricant applied when carrying out tire fitting work.
12. Install the wheel assembly on the vehicle in its place.
13. Additionally, make sure that the actual direction of rotation and that specified by the tread pattern coincide.
14. Check fasteners. Nuts or bolts must match: the thread size - the car; by type of mounting surface (cone, sphere, plane) - wheels; along their length - nuts or bolts must be tightened at least 6 - 8 turns until fully tightened; the thread must be clean, free of dirt, threads must be free of kinks and burrs.
15. Lubricate the fasteners with a drop of machine oil or a small amount of lubricant.
16. Tighten the bolts by sequentially tightening the opposite bolts from the center hole.
17. Tighten the bolts using a torque wrench with the force required for this type of wheel.
Consistent and careful implementation of these actions eliminates the occurrence of vibrations associated with tires and tire fitting work. If vibrations remain after operations, you should check the technical condition of the vehicle.
* “FITTING (OPTIMIZATION)” – the procedure for optimally combining the tire and rim, taking into account their
features. Adjustment can be aimed at 1) reducing the level of runout of the wheel assembly
2) reducing the number of installed weights to eliminate the imbalance. “Fitting (optimization)” to reduce runout and vibration:
18. Measure the level of radial runout of the rim (without tire) - find the place with the lowest level of the rim (closest to the center of the rotation axis); mark it on the inside of the rim so that after mounting the tire, this place will be clearly visible
19. Install the tire, inflate the tire and measure the level of radial runout of the tire. At the point where the tire runs out the most (farthest from the center of rotation), make a mark on the tire.
20. Deflate the tire, remove the tire beads from the tire bead and rotate the tire and wheel to align the marks. Align the marks on the rim and the tire so that they are on the same virtual straight line directed towards the center of the circle.
21. Inflate the tire in two stages, making sure that the tire is correctly installed on the rim flange. Decorative elements of the side zone should be evenly spaced from the edge of the rim. If the shrinkage is not complete, remove the tire, eliminate the cause and re-inflate.
Compliance with the alignment of the marks will result in the lowest level of radial runout and a reduction in possible vehicle vibrations.
If the car pulls to the side
To the consumer
3. Check the direction of rotation of the tires. Does the direction indicated on the bus correspond to the actual direction? If tires with a non-directional tire tread pattern are installed, make sure they are installed with the outer sides (date of manufacture) facing outward (away from the vehicle).
4. Inspect the tires – do all tires have the same tread depth remaining? A significant difference in the tread depth of tires on one axle can cause the car to pull to the side.
5. Check that the installed wheels (rims) and tires comply with the requirements of the vehicle manufacturer.
6. Make sure that vehicle pull occurs on different types of roads and that it is not due to ruts in the road, road grade, or load distribution on the vehicle or trailer.
7. Check the level of tightening of bolts/nuts or other fastening elements of the wheels - the tightening force may have weakened.
8. Check the technical condition of the car: wheel alignment parameter, condition of the brake system, general condition of the car’s chassis.
9. If the above steps do not resolve the problem, you should contact a tire repair shop.
10. Determine when the car starts to pull: when accelerating, when driving at speed, when coasting, when braking, or other options - tell this to a tire specialist or auto mechanic.
INFORMATION SHEET:
The phenomenon when the car pulls to the side can be caused both by the characteristics of the tires and by other reasons:
Materials used (wheels, fasteners...)
The quality of tire fitting work,
The quality of work on installing the wheel assembly on a vehicle
Technical condition of the vehicle (condition of the car hub, condition of the chassis, brake system of the car...)
As well as other reasons not related to tires
To find out the true cause, you should contact a specialized tire workshop or an experienced auto mechanic.
TIRE FITTER OR AUTO MECHANIC
1. Check the internal air pressure in all tires.
2. Make sure that the same tire size, model, design and tread pattern are installed on the same vehicle axle.
3. Check the direction of wheel rotation and compliance with the tire tread pattern.
4. Check tire wear and remaining tread depth. Significant differences in remaining tread depth or differences in tire wear patterns may cause the vehicle to pull to one side.
5. Check that the installed wheels (rims) and tires comply with the requirements of the vehicle manufacturer.
6. Rotate (change installation locations) the wheel assembly on the car and determine the effect of the position of the tires on the degree of “steer” of the car. As a rule, the reason for the car to slip is one, less often two, wheels, and not all four.
7. Use other tires for comparison and determine whether the installation of tires is associated with the “steering” of the car and, if so, which tires?
8. Check the quality of tire shrinkage on the rim. Check wheel runout and balance. If necessary, carry out repeated dismantling/installation/balancing - see above.
If, based on the results of tire rotations and the use of other tires for comparison, it was not possible to determine which tires are the cause of the car’s drift, then you should check the technical condition of the car: the wheel alignment parameter, the condition of the brake system and suspension of the car, steering, as well as other systems and units vehicle.
What to do if balancing requires “a lot” of weights
To the consumer
1. Check the tire inflation pressure. The correct pressure should be set when the tires are cold (not immediately after prolonged continuous use) and should be in accordance with the vehicle manufacturer's recommendations.
2. Inspect the wheels - clean the wheels from dirt, wash them. Inspect the wheels for damage. Carefully inspect the tires - remove all stuck objects from the tread pattern: stones and other objects. Remember that foreign objects: dirt, stones, excess rim repair material, self-installed decorative elements on wheels - can cause increased imbalance, which requires the installation of a relatively large number of weights for balancing.
3. If you have any additional questions, contact a tire repair shop.
5. After tire fitting, eliminate sudden starts and emergency braking from your driving style for a period of one week from the date of tire fitting.
INFORMATION SHEET:
Balancing weights are used in tires to balance the weight of the wheel and ensure uniform rotation without vibration. The amount of weight required to balance a wheel depends on both the level of tire imbalance and the imbalance of the rim used, the quality of tire shrinkage on the rim, as well as the quality of tire fitting work. The number of balancing weights, when installed correctly, does not affect the performance properties of the tires and the vehicle as a whole.
The number of weights glued (by type of fastening) to the rim is not standardized by general GOST standards and other regulations; only the number of padded/clamping (by type of fastening) weights is standardized.
To a specialist
The amount of weight required to balance a wheel depends on the wheel imbalance, tire imbalance, measurement error of the balancing machine and the quality of the tire fitting work. To reduce the amount of weights required to balance the wheel assembly, you should use “adjustment (optimization),” which can be done in two main ways:
1. Thoroughly clean the wheel assembly from dust, dirt and other foreign substances
2. Deflate the tire, remove it and inspect the wheel more carefully:
2.1 Check the condition of the wheel rim - there should be no
but there may be traces of corrosion, dirt and other foreign substances. If there are any substances on the rim, remove them with a brush and/or other means.
2.2 Check the condition of the rim for damage: there should be no dents, cracks, traces of welding or repairs, or geometry corrections. Using a damaged wheel has unpredictable consequences and may require the installation of a large number of weights.
2.3 Measure the runout level of the rim flange. Radial and lateral runout of the wheel rim flange should not exceed 0.5 mm. Runout is measured only by an indicator on a balancing machine or a dial indicator.
2.4 Remove any installed balancing weights and measure wheel imbalance (without tire).
3. Place the wheel without tire on the balancing machine
4. Measure and install the required number of balancing weights so that the wheel (without tire) has a residual imbalance of no more than 5 grams per side
5. Check the condition of the tires - the tires should not show signs of significant repairs, traces of driving with low pressure, damage to the bead or liner. Using damaged tires may require a large number of balancing weights, cause vibrations and be dangerous!
6. Mount the tire on the rim, fix the wheel assembly on the balancing machine using the flange and collet adapters. Flange and collet adapters are special devices that center the position of the wheel on the balancing machine.
(For example, HAWEKA device Attention!
The adapters used should not show any deformation or signs of significant wear.
7. Using the static imbalance measurement program, find the lightest point of the wheel assembly and mark it on the tire with chalk or a felt-tip pen (marker).
8. Deflate the tire and remove any installed balancing weights from the rim.
9. Insert the tire beads into the mounting groove of the rim and rotate the tire relative to the rim to align the chalk mark on the tire and the valve. Align the mark on the tire and the valve so that they are on the same virtual straight line directed towards the center of the circle.
10. Inflate the tire in two stages, making sure that the tire is correctly installed on the rim flange.
11. Maintaining the alignment of the valve and the mark will allow you to connect the heaviest part of the rim and the lightest part of the tire, which will reduce the number of weights required to balance the wheel.
1. Install the tire on the rim, inflate the tire in two stages, ensure that the tire is properly seated on the rim flange, and install the wheel assembly on the balancing machine using the flange and collet adapters.
2. Mark a mark with the number 1 on the outer sidewall of the tire so that this mark is on the same virtual line with the valve and the center of rotation of the wheel assembly on the machine.
3. Turn the wheel assembly 180 degrees on the machine and set another mark with the number 3 on the same outer sidewall of the tire so that the mark is on the same virtual straight line with the valve and the center of the circle.
4. Next, rotate the wheel assembly at an angle of 90 degrees and make two more marks on the sidewalls with numbers 2 and 4 so that the virtual line connecting the two marks with numbers 2 and 4 is perpendicular to the virtual line connecting the marks with numbers 1 and 3.
5. As a result, there should be 4 consecutive marks on the sidewall of the tire, identical to positions 12, 3, 6 and 9 as on the dial of a mechanical watch. The position of the wheel inside the tire will be determined by the tire valve using these marks.
6. First measure the dynamic unbalance* of the wheel assembly with the valve position near the number 1 mark. Record the values with the “1” mark.
7. Remove the wheel from the balancing machine; deflate the tire; remove the tire from the seat; rotate the tire by aligning the wheel valve with mark 2 on the tire; inflate the tire in two stages; make sure that the tire is installed correctly on the rim flange; install the wheel assembly on the balancing machine; measure the dynamic imbalance and record the values with mark 2.
8. Repeat the described steps with marks 3 and 4. Compare the values obtained and select the optimal one.
9. For most situations, it is enough to choose one of four positions
10. In exceptional cases, further adjustments can be made. To do this, you need to reduce the distance between the marks, take measurements and find the most optimal value. Following these recommendations will usually reduce the number of weights required for balancing. However, you should be aware that for each tire size there are tolerances for imbalance. In addition, it should be remembered that at the time of writing this document
on the territory of the Russian Federation there are no uniform tolerances for the mass of corrective weights separately for wheels. Accordingly, following these recommendations will give the most optimal value of correction weights, however, it will not always be able to eliminate it completely.
4. What to do if you can see that the tire has runout (has an “egg” or “figure eight” shape)
1. Check the tire inflation pressure. The pressure should only be checked and adjusted when the tires are cold (i.e. not immediately after prolonged continuous use) and must comply with the vehicle manufacturer's recommendations (see the factory information badge (sticker, sticker), which is usually located on the gas filler flap or in the driver's door opening doors).
2. Do not try to visually assess the degree of tire runout. It is not right. The human eye is not the most accurate instrument, and visually a runout of 0.3 mm is perceived by a person as critical, although in fact it is not. Accurate values can only be obtained by measurement using specialized means.
3. To measure the runout value, contact a tire shop.
4. Assess whether the detected beating causes any inconvenience: steering wheel vibrations, car body vibrations, uneven tire wear, car pulling to the side... Provide this information to a tire fitter or auto mechanic.
5. Inspect the tires for wire threads coming out of the rubber compound and for internal delaminations of the tire. If you find something, go to a tire shop and report it to a tire fitter or auto mechanic.
6. After tire fitting, eliminate sudden starts and emergency braking from your driving style for a period of one week from the date of tire fitting.
To a specialist
1. Check the tire's internal air pressure.
2. Inspect the tires for wire threads coming out of the rubber compound and for internal delaminations of the tire
3. Measure the radial and lateral runout of the tire. Radial runout should not exceed 1.5 mm, lateral runout 2 mm.
4. If the measured values satisfy the specified restrictions and no delaminations or wire exits are detected, then everything is in order and operation can be continued.
5. If the measured values satisfy the specified restrictions, then check the condition of the wheel and tire according to the scheme described in section 1 from external inspection to re-mounting and balancing (points 1 to 19).
End (axial) runout of a wheel occurs during rotation and looks like an oscillatory movement of the wheel rim humps in a plane parallel to the axis of rotation.
Radial runout occurs under similar conditions, but means oscillatory movements of the wheel rim in a vertical plane.
In the figure on the left you can see a schematic representation of both types of runout.
Large values of axial runout are often the result of wheel impacts during a side collision with a curb. Sometimes this can be seen when a jeep skids on a slippery road. Exceeding the radial runout value appears as a result of a strong frontal impact on the wheel, that is, when colliding with a pothole or hole. But more often than not, the consequence of a “good” blow will be the presence of both types of runout. In pronounced cases, the steel disc gets dents on the edges of the rim, chips, and “figure eights” visible to the naked eye when rolling.
What is considered an excess?
In accordance with the domestic standard GOST R 50511-93, the runout of a passenger car wheel rim in the tire contact area (humps) should be no more than 0.5 mm in any type of runout. This standard also applies to SUVs.
Do not try to determine the amount of runout of a steel disk visually, since in this case vision will not allow you to accurately assess the size of the deviation. In some cases, with such small beating sizes as 0.3 mm, the average person becomes convinced of its prohibitive size. For accurate measurements, a clock or electronic indicator must be used, which is located on the axis of symmetry of the jeep rim.
The most common causes of beating
A significant part of the causes of runout is not related to changes in the geometry of the alloy wheel of an SUV, but relates to production or operational issues:
- Uneven paint coating on the mating surface of the disk
- Sticky pieces of road surface and dirt
- Presence of debris and foreign inclusions on the balancing stand flange
In other words, you should not always blame yourself or the previous owner of the car for an unacceptable amount of runout. The reason may be more prosaic and may not require large investments to eliminate.
Every driver has encountered vibrations and impacts on the steering wheel while driving; in many cases, the wheel runout, or rather its incorrect balancing, is to blame. The wheel must be perfectly shaped. Size and other factors may also have an impact. But, most often the problem is solved by simple balancing. Let's look at what balancing is, what it is like and how to do it correctly. 
Wheel runout - what is it? Types of wheel runout
Wheel runout is the displacement of the disk during movement, can be radial or axial. Either way, you will get vibration or shock. The higher the speed, the more noticeable the problem becomes.Let's look at the varieties in more detail.
- Axial runout is the horizontal displacement of the wheel. Typically this disk behavior is called “figure eight”. Usually caused by an imbalance in the distribution of mass on a plane.
- The cause of radial runout is static imbalance. At the same time, the disk begins to resemble an egg in shape. Oscillatory movements occur up and down. Usually accompanied by variable torque.
It is worth considering what could be a consequence of such a phenomenon. With axial runout, the main consequences are the following:
- damage to the steering mechanism and chassis;
- increased tread wear, which leads to rapid tire failure.
It is also worth separating dynamic and static imbalance. There are some peculiarities here, primarily in terms of how to solve the problem.
With static imbalance, the torque is created by the weight of the unbalanced mass. Simply put, the wheel will rotate without interference until the unbalanced mass is in its extreme position. Thus, the movement of the wheel resembles a pendulum.
In the case of dynamic imbalance, the wheel rim is unbalanced in width. It can only be observed while rotating. In case of such a problem, the axis of rotation is completely misaligned with the main central axis of inertia. In fact, a certain angle is formed between the axes. At the same time, the presence of two centers of mass in different parts of the wheel causes a dynamic imbalance. During movement, centrifugal forces arise, they act in opposite directions and manifest themselves in the form of wheel beating.
How does wheel runout manifest itself?
In practice, the driver most often notices the beating when driving. Moreover, the wheel begins to beat even on a flat road, and the higher the speed, the more intense the impacts. In many cases, the steering wheel begins to hit, which may begin to vibrate. The car becomes less controllable.
The relationship between speed and beat amplification is explained by a simple reason. The imbalance has a certain period, for example two meters. The faster the car moves, the more often the cause of the beating is repeated; accordingly, the higher the speed, the more noticeable the problem. The magnitude of the imbalance also affects.
In some cases, it may occur during braking. Here we are talking more about static imbalance of the wheel. This is often evidenced by vibration of the wheels when applying the brakes. The cause is often the destruction of the hub bearings or problems with the brake mechanism.
Separately, it is worth examining the reasons for the appearance of imbalance. Let's list the main ones.
- Mechanical damage and deformation of suspension parts. In fact, a wheel consists of more than just a disc and a tire; there is also a hub, a brake caliper, and a disc. If they are deformed, this can also cause wobbling.
- Deformation of the wheel rim. During operation, the geometry of the disk may change.
- Uneven tire wear. First of all, we are talking about tread wear within one wheel. But, in practice, there is also the problem of uneven tire wear on different wheels of the same axle. If one wheel has more than 1.5mm of pattern wear, it will also cause runout.
- Incorrect wheel replacement. In fact, the reason is quite common. When installing a spare tire, drivers often perform the final tightening of the wheel after lowering the jack. This can cause the disk to shift by millimeters relative to the axis, and accordingly, runout appears.
How to check a wheel for runout
An important point is the diagnosis of this phenomenon. The difficulty is that tire runout is very difficult to diagnose. Noticeable impacts occur only at high levels of disturbance. Therefore, it is recommended to check periodically. Be sure to check both the rear and front wheels. It is especially important to carry out this diagnosis if you are changing tires, or if there is any vibration on the steering wheel.
If there is a suspicion that the wheel is not bent. First, check for geometric imbalance. To do this, the car wheel is hung up, and while spinning, the level of runout is measured with a special device. If the parameter exceeds 0.5 mm, the cause should be identified and eliminated. After checking for geometric imbalance, it is worth removing the wheel and performing balancing on a special machine. This should eliminate runout almost completely.
Consequences of wheel runout
The most obvious consequence of runout is rapid tire wear. They begin to wear off unevenly, which worsens their technical characteristics.
Another point that is less obvious is damage to the suspension and steering. Runout is characterized by impacts on the chassis elements associated with the wheel, as well as steering mechanisms. This leads to their rapid failure.
Another possible problem is deterioration in controllability. With strong impacts, there is a risk of losing control of the car. The result could be an emergency on the road.
