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Recently, papers have been published purporting to study the effect of rear axle tramp during tread separation events, and its effect on vehicle handling [1, 2]. Based on analysis and physical testing, one paper [1] has put forth a mathematical model which the authors claim allows vehicle designers to select shock damping values during the development process of a vehicle in order to assure that a vehicle will not experience axle tramp during tread separations. In the course of their work, “lumpy” tires (tires with rubber blocks adhered to the tire's tread) were employed to excite the axle tramp resonance, even though this method has been shown not to duplicate the physical mechanisms behind an actual tread belt separation. This paper evaluates the theories postulated in [1] by first analyzing the equations behind the mathematical model presented. The model is then tested to see if it agrees with observed physical testing.

There has been very little investigation into the area of tire aging and whether storing a tire will change it's properties, in particular ‘limit’ or ‘saturated’ properties, over time. In order to study how the performance characteristics of tires change when the tires are stored, a series of force and moment tests were performed on five modern day radial tires of different make, brand, type, and size. The tires were all purchased at the same time for a given tire set and had the same DOT code. Near the date of purchase, some of the tires were tested on the Veridian TIRF (Tire Research Facility) machine in order to measure their force and moment characteristics. Other tires of the lot were placed on a tire rack in a storage building. Years later, these tires were sent to the same test facility and were measured under the same test conditions. The data indicates that tire performance characteristics change very little with time.