Appeal No. 2001-0780
Application No. 08/997,368
a tapered top end over a range of 10-30 mm in a longitudinal
direction of the block so as to gradually shallow a depth of a
surface of the block from the tapered top end toward an opposite
end of the block. This appealed subject matter is adequately
illustrated by independent claim 1 which reads as follows:
1. In a pneumatic radial tire for all-season passenger car
comprising; a tread with a tread pattern defined by dividing the
tread into many blocks through a plurality of slant grooves
arranged at given intervals in a circumferential direction of the
tire and at least one circumferential center groove extending in
the circumferential direction of the tire at a center portion of
the pattern, and consisting of a central zone having a width
corresponding to 30-60% of a tread width and a pair of side zones
located on both sides of the central zone; wherein
(1) the slant grooves comprise steeply slant grooves extending
at a relatively small inclination angle with respect to the
circumferential direction and gently slant grooves extending at
a relatively large inclination angle with respect to the
circumferential direction;
(2) the steeply slant grooves are opened to the circumferential
center groove in the central zone of the tread, while the gently
slant grooves are opened to a tread end in each of said side zones
of the tread to form blocks in said side zones;
(3) the number of the gently slant grooves is made two or
more times than the number of the steeply slant grooves so
that an interval between the gently slant grooves in the
circumferential direction is made 1/2 or less than an interval
between the steeply slant grooves in the circumferential direction;
(4) each of the blocks is provided with at least one sipe; and
(5) blocks formed in the central zone are defined by the
circumferential center groove and the steeply slant grooves and
are chamfered from a tapered top end over a range of 10-30 mm in a
longitudinal direction of the block so as to gradually shallow a
2
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