Resilient tires and wheels – Tires – resilient – Anti-skid devices
Reexamination Certificate
1999-03-01
2001-06-26
Maki, Steven D. (Department: 1733)
Resilient tires and wheels
Tires, resilient
Anti-skid devices
C152S209210, C152S903000, C152SDIG003
Reexamination Certificate
active
06250354
ABSTRACT:
BACKGROUND OF INVENTION
The present invention relates to a vehicle tire suitable for running on ice-covered roads, more particularly to an improved tread portion of a rib-block tread pattern capable of improving on-the-ice performance.
DESCRIPTION OF RELATED ART
In general, pneumatic tires called “winter tire”, “snow tire”, “studless tire” and the like used on snowy and icy roads are provided in the tread portion with a number of blocks to obtain a good on-the-snow performance. And, a large number of sipes are disposed on the blocks to increase edges to obtain a good on-the-ice performance.
Further, rib-block patterns comprising blocks and a circumferential rib are also popular in pneumatic tires for used on ice-covered well-paved roads such as asphalt road. Such a circumferential rib is also provided with sipes in order to improve on-the-ice performance.
In such rib-block patterns, however, as shown in
FIG. 8
, as the sipes (b) close in the ground contacting patch, the circumferential rib (a) behaves like one body although it is divided by the sipes (b), and the apparent rigidity in the circumferential direction is still high. Thus, the parts (a
1
) divided by the sipes hardly lean towards one circumferential direction. Accordingly, it is difficult for the edges of the sipes (b) to scratch or engage with the iced road surface. If the spacings of the sipes (b) are decreased in order to decrease the apparent rigidity, the parts (a
1
) suffer from uneven wear, cracks and tear-off. Thus the durability greatly decreases.
SUMMARY OF INVENTION
It is therefore an object of the present invention to provide a pneumatic tire in which, parts of a circumferential rib divided by sipes are leant appropriately without decreasing the apparent rigidity of the rib, and accordingly, the edges thereof effectively engage with the road surface to increase the traction without deteriorating the durability.
REFERENCES:
patent: 2716435 (1955-08-01), Herzegh
patent: 4481992 (1984-11-01), Takigawa et al.
patent: 5386861 (1995-02-01), Overhoff et al.
patent: 5785780 (1998-07-01), Ochi
patent: 5873399 (1999-02-01), Ochi et al.
patent: 330643 (1989-08-01), None
patent: 715972 (1996-06-01), None
patent: 61-1508 (1986-01-01), None
patent: 63-291705 (1988-11-01), None
patent: 3-271007 (1991-12-01), None
patent: 6-312603 (1994-11-01), None
Birch Stewart Kolasch & Birch, LLP.
Maki Steven D.
Sumitomo Rubber Industries Ltd.
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