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The paper has two objectives - (1) to describe the manner in which tires are involved in the “torsional nibble” disturbance an occasional problem in vehicle development, and (2) to illustrate a generally applicable approach for diagnosing the relationships between tire properties and subjective disturbances.

Engineers who are developing new models of vehicles invest considerable effort in adjusting the steering characteristics to conform with specific commercial objectives. In this process, tires have to be redesigned so that their steering properties match the requirements imposed by the physical nature of the vehicle and the subjective reactions of test drivers. One method for the identification of the underlying physical system, and the determination of the required tire properties proceeds by the general approach outlined in the paper.

The A-weighted sound level accounts for the bulk (but not all) of the jury's reaction to the sound of trucks coasting on a variety of tires. A component of the jury's reaction is related by the study to the manner in which the sound decays after the vehicle passes the point of observation. This component also appears to depend strongly on the characteristics of the sound. The jury's reaction shows two forms of distortion: end-of-scale compression and temporal drift. The analysis attempts to account for these factors and to see beyond them into the jury's basis for reacting.

The rolling resistance of a tire can have a marked effect on such factors as gasoline mileage and high speed durability. In an effort to understand better the mechanisms involved, 80 tires were analyzed. This analysis resulted in dividing the rolling resistance into a component (Ra) independent of speed, and a component (Rb), which is very speed dependent. The body of this paper discusses the effect of operating conditions and tire design variations on both of these components.

An engineering project to minimize rolling resistance of passenger car tires, with special emphasis on construction and materials, is described. Both empirical and theoretical approaches were employed in the study. Designed experiments, special experimental setups, and novel statistical methods were used to maximize the information obtainable from experimental tires. A reduction of more than 20% in the rolling resistance of the subject tires, size P185/80R-13, was achieved within stated design parameters, while performance properties were maintained

This paper discusses snow testing of passenger and light truck tires, utilizing a self-contained instrumented driving traction test truck. It compares the test results of snow traction performance to empirical predictions. Tire test design parameters of lateral density, sipe density, tread depth and tread width are examined. It is recognized that additional work is required to further establish these relationships.

Disturbances transmitted to the occupants of vehicles often involve tires in their formation or transmission. Tire engineers attempting to reduce disturbances in specific vehicles have two courses of action; alter the tire design according to insight or whim until subjective testing indicates improvements; or analyze the chain of relationships from sensory impression through the tire-vehicle system to internal tire design. This paper describes a “chain-of-relationships” procedure using sensory comparison techniques for identifying pertinent physical stimuli, and an approach to system modeling that best identifies structural tire properties.

A study of the role of tires in the ride-disturbance created in passenger cars by longitudinal grooves in highway pavements is presented. The coincidence of groove spacing in pavement and groove spacing in tires is shown to be of major importance. Tire construction and operating conditions are shown to be secondary. A methodical approach for evaluating tread patterns for potential disturbance is described.

This presentation is a sequel to Paper 762035 in that an alternate method of testing for tire noise is investigated and the results of experimental studies are described. The alternate method is designed so as to preserve in the proposed measurements, the pertinence of J57a. Comparative testing of numerous tire designs in the two manners shows that this objective has indeed been accomplished. Rather than presenting the experimental details behind each of the various foundations for the proposed method, this paper confines its discussion to the items significant to the description of the method and to a comparison with the J57a procedure.

The objective of the investigation is to provide a basis for judging whether or not the dynamic steering adjustments of the tire forces affect vehicle performance in a significant manner. The differential equation of cornering force adjustment is developed from experimental data. This equation is applied, for a typical radial ply tire, to a crude but sufficient mathematical model of a vehicle. The responses of the vehicle in certain maneuvers differ to some degree when the model is programmed with instantaneously reacting tires or with simulations of actual tires. The authors judge that there are slight and unimportant effects on the path and heading curves of the vehicle due to the delays in build-up cornering force. On the other hand, there appear to be detectable effects that may be important in the sensory information provided to the driver.

The paper treats the following: a. The basic mechanical processes leading to the formation of the rolling resistance of radial ply pneumatic tires, b. Special testing procedures for elucidating the contributions and characteristics of these mechanical processes, c. An assessment of the relative contributions to the rolling resistance from various mechanisms and parts of the tire.