Passenger tire having low rolling resistance with improved wet traction and treadwear

Abstract

A tire having a tread includes an outer tread layer and an inner tread layer. The inner tread layer includes one of a first elastomeric compound and a second elastomeric compound. The outer tread layer includes the other of the first and second elastomeric compounds. The second elastomeric compound has a lower rolling resistance and greater resistance to treadwear than the first elastomeric compound. The inner tread layer increases in thickness across at least a widthwise portion of the outer tread layer with a maximum thickness of one of the inner tread layer and the outer tread layer occurring near at least one of a first shoulder and a second shoulder of the tread. As the tread wears, the inner tread layer defines a greater proportion of a running surface of the tread.

Description

CROSS REFERENCE TO RELATED APPLICATION[0001]This application is a Divisional of U.S. patent application Ser. No. 12 / 956,870, entitled “Passenger Tire Having Low Rolling Resistance with Improved Wet Traction and Treadwear,” filed Nov. 30, 2010 (pending), which claims the benefit of and is a continuation application of U.S. patent application Ser. No. 12 / 943,584 entitled “Passenger Tire Having Low Rolling Resistance with Improved Wet Traction and Treadwear” filed Nov. 10, 2010 (abandoned), the disclosures of which are hereby incorporated by reference in their entirety herein.FIELD OF THE INVENTION[0002]The present invention generally concerns pneumatic radial tires, and, more particularly, a radial tire for a passenger vehicle that maintains a low rolling resistance while having good wet traction and treadwear throughout the usable life of the tire.BACKGROUND OF THE INVENTION[0003]The primary purpose of the tread is to provide traction with the road surface. Sufficient traction is par...

AI Technical Summary

Benefits of technology

This design maintains consistent rolling resistance, traction, and treadwear characteristics throughout the tire's life, reducing fuel consumption and extending tire life while maintaining wet traction, even as the tread wears down.

Problems solved by technology

Compositions with good traction are known, but simply selecting a composition for improved traction can have negative repercussions on the other characteristics of the tire, as set forth below, such as the wear resistance and rolling resistance.

However, while compounds having low rolling resistance are desirable for improved fuel efficiency, those same compounds often do not provide the necessary minimum traction.

That is, a compound with good traction properties typically exhibits an unacceptably high level of rolling resistance.

However, similar to the competing characteristics between rolling resistance and traction characteristics of the tread, set forth above, compounds that are ideal for reducing treadwear typically exhibit poor traction.

Since the tread pattern is primarily responsible for allowing the tread to maintain traction on wet or snow covered roads, reduction in the thickness of the tread, and the consequential loss in the void volume and sipping depth of the tread pattern, reduces the traction of the tread in these circumstances.

Therefore, where rolling resistance generally decreases, which is a desirable trend, the traction of the tread in inclement weather also decreases, which is an undesirable trend.

However, where one of the characteristics is emphasized, the remaining characteristics of the tire can be less than optimum.

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