Resilient tires and wheels – Tires – resilient – Anti-skid devices
Reexamination Certificate
1999-03-19
2001-04-24
Maki, Steven D. (Department: 1733)
Resilient tires and wheels
Tires, resilient
Anti-skid devices
C152S904000
Reexamination Certificate
active
06220324
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle tire having an improved tread pattern capable of improving off-road grip such as traction and side grip, and more particularly to an asymmetrical tread patterns specialized for right tire and left tire.
In order to improve road grip during off-road running such as side grip, traction, braking and the like, many attempts have been made, and it has been believed that important factors in improving road grip are the inclination of the edges of tread elements such as blocks and the like, namely the inclination of tread grooves defining such elements, and the lengths of the edges. Hitherto, therefore, when much importance is attached to the traction performance, the total length of axially extending edges has been increased. On the other hand, when much importance is attached to the side grip performance, the total length of circumferentially extending edges has been increased. However, it is difficult to effectively improve the road grip in all directions, traveling direction i.e. in the and in the side direction.
SUMMARY OF THE INVENTION
It is therefore, an object of the present invention to provide vehicle tires, in which off-road grip performances such as traction and side grip are effectively improved.
The present invention is based on the fact that the outside part of the tread with respect to the vehicle has a greater influence upon the side grip than the inside part, but the inside part of the tread has a greater influence upon the traction performance than the outside part. Therefore, the tread pattern is changed between the outside tread part and inside tread part such that the inclination of tread grooves is macroscopically steeper in the outside tread part than the inside tread part.
According to one aspect of the present invention, a vehicle tire comprises.
a tread having an outside tread edge and an inside tread edge to be placed on the outside and inside of a vehicle, respectively.
The tread comprises an inside tread part extending from the inside tread edge toward the tire equator, and an outside tread part extending from the outside tread edge toward the tire equator.
The inside tread part is provided with inside axial grooves extending axially across this part so as to circumferentially divide this part into blocks.
The outside tread part is provided with outside axial grooves extending axially across this part, and outside circumferential grooves each extending between the circumferentially adjacent outside axial grooves so as to circumferentially and axially divide this part into blocks, wherein, when looking down on the tire, the outside axial grooves are inclined toward one direction such that the outer ends thereof are positioned backward of the inner ends with respect to an intended traveling direction, the inclination angle &agr; of the outside axial grooves is in the range of from 60 to 80 degrees with respect to the tire equator C.
The outside circumferential grooves are inclined toward one direction such that the outer ends thereof are positioned forward of the inner ends. The inclination angle &ggr; of the outside circumferential grooves is in the range of from 15 to 45 degrees with respect to the tire equator C.
The inside axial grooves are inclined at an angle &bgr; of 80 to 110 degrees with respect to the tire equator C, wherein the direction for measuring the angle &bgr; is such that when the angle &bgr; is less than 90 degrees, the inclination thereof is the same direction as the outside axial grooves.
Preferably, the inside tread part is provided with inside circumferential grooves each extending between the circumferentially adjacent inside axial grooves. The inside circumferential grooves are inclined towards the same direction as the outside circumferential grooves, at an angle &dgr; of more than 0 degree with respect to the tire equator C but less than the angle &ggr;.
REFERENCES:
patent: D. 336068 (1993-06-01), Attinello
patent: 4984616 (1991-01-01), Shepler et al.
patent: 5415215 (1995-05-01), Covert et al.
patent: 5658404 (1997-08-01), Brown et al.
patent: 5702545 (1997-12-01), Toyoshima et al.
patent: 5967210 (1999-10-01), Himuro
patent: 539346 (1993-04-01), None
Birch & Stewart Kolasch & Birch, LLP
Maki Steven D.
Sumitomo Rubbert Industries, Ltd.
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