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The ease or difficulty of mounting a tire on a rim depends on many factors which can be quantified by the torque that must be applied by a tire mounting machine on the tire. It was determined that the in plane and out of plane stiffnesses of an un-mounted tire have significant influence on this mounting torque. In addition, it was observed that a lateral deformation applied on the tire sidewall and the bead can also influence the mounting torque and this effect depends on the un-mounted tire stiffnesses. These observations can be explained based on the mechanics of the tire mounting process. Case studies will be presented to illustrate the influence of tire stiffness and deformations on mounting difficulty. Tests that were developed to measure the tire stiffnesses and mounting torque will also be discussed.

Tires flatspot when they remain loaded without rolling for a period of time. When the tires are rolled again, the initial flatspot decays and vanishes or stabilizes to a much smaller magnitude (called residual flatspot). Flatspot is a low harmonic phenomenon and primarily contributes to the first three or four harmonics of tire run out. The tire non uniformity caused by a flatspot may induce noticeable vibrations in some vehicles during operation in the decay process. The magnitude and decay of a flatspot depends on many factors - tire construction, material creep properties, tire radial load and time duration, inflation, tire and ambient temperatures, tire mileage, etc. In this paper, the fundamental concepts involved in the formation and decay of flatspot are discussed. These characteristics can be objectively measured in a laboratory and flatspot trends can be explained.

One of the primary functions of automobile suspension bushings is to isolate the vibrations being transmitted from the suspension to the passenger compartment. Under certain operating and road conditions, the viscoelastic characteristics of the rubber bushings are not sufficiently high to damp out the road disturbances. Also, small amplitude disturbances from the road at the tire foot prints are usually too small to activate the shock absorber and hence are not easily damped out. Low torque bushings can improve this situation using Coulomb damping which is generated by providing a slip surface between the rubber and the inner or outer metal. This construction therefore allows the possibility of controlling the torsional deformation and limiting the torque transmitted under service conditions by adjusting the torque required to slip. In this paper, we study the behavior of low torque bushings in an automotive rear suspension and compare their performance against conventional bushings.