1. Field of the Invention
The present invention relates to tires, wheels and the mounting of tires on wheels.
2. Description of the Related Art
Conventionally, tires and wheels have been able to be separated from one another, and the wheel itself is fastened in a removable way to its hub. The wheel comprises a rim, which, with the tire, delimits the tire chamber filled with air under pressure. It also comprises a disk intended to be fastened to the hub. The rim is fastened to the disk either in a definitive way (rivets, welding), or in a removable way.
The tire is removable from the rim for permitting the necessary repair in case of a flat and for permitting the replacement of the tire when it is worn. This removal requires workshop equipment and, at each removal/mounting, it is necessary to perform a new balancing of the unit. The removal of the wheel in relation to the hub is very simple and within the capability of the user who must be able to perform this operation to perform a repair: in case of a flat, he removes the wheel concerned and mounts a spare wheel.
The association of the tire and its rim entails several problems. To assure the fluid tightness of the unit, and also to be able to transmit a torque, there is always a squeezing between the tire and the rim, more specifically between the lower face of the bead of the tire and the seat of the rim. The precise position of the bead on its seat is determined by the rim flange which acts as a stop against which the bead is flattened by the inflation pressure.
But, because of the squeezing on the seat, the exact position of the bead is poorly controlled: the plane that it makes, indicated for example by a plane tangent to the bead wire, cannot be absolutely parallel to the rim edge. The bead wire cannot be perfectly concentric to the seat of the rim even in the absence of any defect of shape of the tire. In driving, a wearing of the tire sometimes appears, caused by slight relative movements of it in relation to the radially upper end of the rim flange.
The constant increase in the performances of motor vehicles, in particular passenger cars, and the constant increase in the quality of the behavior of them necessitates shrinking ever more the production tolerances of tires. It is found that the mounting of the tire on its rim can obscure the performances of the tire: when the behavior of a vehicle is rated, differences can be observed that are as great, indeed greater between two runs with the same tire or tires that have been simply removed then remounted between the runs, than between runs with different tires that are being sought to be classified. This shows the precision, the fineness of reaction that is expected from the tires, and this also illustrates the difficulties that there are in improving the behavior of the vehicles if the mounting of the tire on the rim is insufficiently controlled.