Method of improving steering performance robustness utilizing stiffness non-uniformity in tire/wheel

#This invention relates to methods of improving the steering performance of vehicles, particularly passenger vehicles having pneumatic tires.

#The term “steering performance” (or simply “steering”) refers to a vehicle driver's feeling that a vehicle's steering (and/or “handling”) is responsive to movement of the steering wheel. The better the steering performance, the better the driver's “feeling” of having control over the vehicle's steering. Because it relates to a “feeling” on the part of a driver, steering performance is essentially a subjective evaluation of a vehicle's steering. Steering performance can change over time, mainly deteriorating as components in the vehicle steering system wear, age, or suffer damage. Steering system components include the steering wheel, the tires and wheels, and everything in between such as the steering box, any power assist components, and linkages and joints. Steering performance can also vary with operating conditions, including, for example, road texture, vehicle speed, steering wheel settings, minor tire inflation pressure changes, and tire/wheel uniformity changes (e.g., balance).

#Worsening steering performance is generically referred to as “steering performance loss” (SP-Loss), or “give-up”. A steering system or component which is resistant to steering performance loss is “robust” or can be said to possess “steering performance robustness”. Similarly, any component change which appears to delay or prevent SP-Loss in a vehicle steering system can be said to improve steering performance robustness. Also, it has to be mentioned that SP-Loss is more noticeable on vehicles which have, in general, a very good and crisp steering. Finally, it has been noted that steering component changes which improve steering performance robustness usually also enhance the driver's perception of steering performance. The inverse may not be true, i.e., a component change which enhances steering performance initially may not be robust and therefore quickly deteriorates to yield a net steering performance loss.

#Reference will be made in detail to preferred embodiments of the invention, examples of which are illustrated in the accompanying drawing figures. The figures are intended to be illustrative, not limiting. Although the invention is generally described in the context of these preferred embodiments, it should be understood that it is not intended to limit the spirit and scope of the invention to these particular embodiments.

#Certain elements in selected ones of the drawings may be illustrated not-to-scale, for illustrative clarity. The cross-sectional views, if any, presented herein may be in the form of “slices”, or “near-sighted” cross-sectional views, omitting certain background lines which would otherwise be visible in a true cross-sectional view, for illustrative clarity.

#Elements of the figures can be numbered such that similar (including identical) elements may be referred to with similar numbers in a single drawing. For example, each of a plurality of elements 199 may be referred to individually as 199a, 199b, 199c, etc. Or related but modified elements may have the same number but are distinguished by primes. For example, 109, 109′, and 109″ are three different elements which are similar or related in some way, but have significant modifications e.g., a tire 109 having a static imbalance versus a different tire 109′ of the same tire construction, but having a couple imbalance. Such relationships, if any, between similar elements in the same or different figures will become apparent throughout the specification, including, if applicable, in the claims and abstract.

#Definitions

#The following terms may be used throughout the descriptions presented herein and should generally be given the following meaning unless contradicted or elaborated upon by other descriptions set forth herein.

#“Axial” refers to a direction parallel to the axis of rotation of the tire.