In a wheel (tyre, inner tube, fitting rim, brake drum, etc.) the weights are generally never evenly distributed, both along the circumference and transversally. This causes various tyres of vibrations which are transferred to the vehicle from the wheel both through the drive elements and through the suspension. The amplitude of the vibrations is proportional to the size of the weights and depends on the speed rating. In order to eliminate these vibrations, balancing is performed by adding one or more weights (counterweights) applied to the rimbalconies. Three types of imbalance can be identified: static, dynamic and torque. Fixed or mobile installation balancing machines are generally used for balancing a wheel.

The area of the mounted tyre which seats against the wheel.

Strip of fabric located between the bead assembly and the bead filler, with the function of increasing the attachment surface compared to the carcass plies and of increasing the rigidity of the bead.

It is the concave part of the bead on which the balcony of the rim rests.

It is a metal ring made up of several steel wires. The plies of carcass are fixed to the bead core.

It is a generally triangular section rubber profile positioned above the bead core; it gives rigidity to the bead and creates a gradual compensation to the sudden discontinuity of thickness caused by the bead core.

It is a small rise which circumferentially limits the upper part of the bead, it is a reference to control the exact centring of the tyre on the rim after fitting.

With low inflation pressure in a tubeless tyre and with transversal thrust, the bead comes out of its seat in the rim with the consequent loss of air.

It is a metallic or textile material insert, arranged near the external part of the heel; it protects the carcass plies from rubbing against the rim.

They are the elements of the suspension of a vehicle which mechanically connect wheel and body ensuring the required degrees of freedom and the position of the wheel compared to the body; they are: swinging arms, stub axles, supports, joints, tie bars, etc.

It is the wheel whose job it is to support the vehicle. The term bearing attributed to the wheel refers to its function of supporting the vehicle.

The dynamic behaviour of the vehicle, according to the tyre fitted may be described by means of a large number of items, each one regarding a certain phenomena, and evaluated by sensation by specially trained testers. These items together define the evaluation form of the tyre (dry road classification) and can be combined in four fundamental areas: Straight line driving, soft handling, hard handling and Comfort.

It is a non extendible circumferential structure consisting of crossed plies with very low corners; positioned under the tread, with the aim of stabilising the carcass in the contact area, distributing the load in the section of the tyre, contributing to the driving characteristics. It may be of steel, nylon, rayon and kevlar.

Particular tyre structure in which the carcass ply cords are laid at alternate angles so that the cords making up a ply cross with those of the adjacent ply. The plies must always be laid in pairs for construction symmetry so that there is always an even number of them. This structure is, in any case, being abandoned for the radial structure.

Individual element of the tread pattern. The block may be quadrangular, trapezoid, rhomboid, circular, polygonal, etc. according to the tread pattern.