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Inbalance of wheels

Inbalance of wheels - the types and causes of

Balancing wheels of the vehicle is a matter in modern  motorization quite simple, but touching each driver and each vehicle. Even the new car and its shiny new wheels need extra weights that balancing kit. Why is that and what it means for the driver and his vehicle?

Inbalance new tires and wheels is caused usually by inhomogeneity of the material from which they are made. Even the best tyre products and expensive, expensive wheels mounted  must be balanced. With a weight wheels constituting a dozen, and sometimes more kilograms imperfections with a mass of a few grams seem negligible.

The problem is that the wheel of a car rotates very quickly. If we assume that its diameter is 40 centimeters, then at a speed of ~ 100 km / h wheel rotates up to ~ 22 times per second. Then it soon becomes clear that even the smallest imbalance is a serious problem. What are the types of wheel imbalance and how they affect the operation of the car?

Types of unbalance

The first type is static unbalance. It consists in that the axis of rotation of the wheel does not cover with the axis of inertia. This results in periodically variable centrifugal force, which amplitude is dependent on the size of the wheel unbalance. This force acts in the direction perpendicular to the axis of rotation. Even when it is low and the driver is unable to see her, this causes cyclic loading small forces element of suspension and bearings, causing premature wear.
The second kind of inbalance is a dynamic inbalance, which has resulted in the creation of moments of centrifugal forces, that is the forces acting on a specific arm. Dynamic inbalance is caused when the axis of rotation of the wheel cuts the main axis of inertia out of the center of mass. Then become the vibration parallel, and a wheel popularly call a wheel centered. Such loads also affect the additional wear.

But the everyday use of the vehicle is not the world only in black and white, because wheel inbalance is usually a combination of static unbalance, which may be, for example microdamages of tires and the dynamic in the form of soiling the outer part of the rim or her concavity. What are the most common causes of such imperfections of the wheel – tire system?


Besides these heterogeneity we meet primarily exploitationed causes. Vehicle wheels encounter daily and  surface defects and omnipresent and  from year to year higher curbs. Only outwardly this exploitation no trace on them, because microcracks tires leave their mark on it. The same is true with invisible at first glance damaged rims. But modern cars are getting bigger wheels and more and more low-profile tires. It is more and more difficult to travel all tiring season without a single knocing down wheels on the hole, or scratch the surface of the curb.

Well, that although one reason for the formation of the tire unbalance is becoming more and more rare. In times of popularization of ABS-u more and more rarely to flatten tires as a result of rapid braking with locked wheels. Yes, daily driving is not Formula 1, but once it was frequent and what older drivers remember after such an emergency maneuver, often appear vibrations on the steering wheel.

How do you recognize?

The easiest way to get to know the unbalance of the front wheels is vibration on the steering. Typically, they appear in a range of speeds, dependent on the inbalance and the frequency of free vibrations of wheel-tire system. When unbalance will cause vibrations at a frequency close to the  frequency free vibrations resonance phenomenon arises - further strengthen and their propagation. Inbalance rear wheels usually more difficult to observe, because then the vibration enters all the car and the average driver could hardly finds the cause.

The drivers most often prepared  often walk into a trap - those who hide in their homes a second set of tires setted on the rims and often they change themselves. Nothing wrong with that, but the old mantra says that the wheels must balance every 10 000 km - many usually do not want to just go to the vulcanizer. The latter also throw in thier two cents' worth and see a strange look when someone wants to simply balance the wheel.


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