Appeal No. 1999-1835
Application No. 08/654,976
second edge region and the central region of said
island portion in a substantially axial direction, and
a return segment whose tip is turned back at a first
interface between the central region and the first
edge region or in the vicinity thereof and which is
terminated within the central region of said island
portion;
whereby said first and second sipes divide the
central region of said island portion into a large
number of island elements compared to the edge regions
thereof.
8. A studless pneumatic tire in which a
plurality of block-shaped island portions each having
sipes are provided on a cylindrical tread extending
between a pair of annular sidewalls, wherein
said tread has at least two rubber layers having
different hardnesses, and
the tread has at least one area having soft
rubber and hard rubber and including sipes, the tread
has at least one other area having soft rubber and
hard rubber and including sipes, the density of the
sipes in the at least one area is larger than the
density of the sipes in the at least one other area,
the density of the sipes being defined as a total
projected length of portions of the sipes within an
area, the ratio of the volume of hard rubber to the
volume of soft rubber in the at least one area is
larger than the ratio of the volume of hard rubber to
the volume of the soft rubber in the at least one
other area.
10. A studless pneumatic tire according to Claim
8, where each island portion comprises:
a first sipe which has an extension segment
extending from a first lateral end of said island
portion and traversing a first edge region and a
central region of said island portion in a
substantially axial direction, and a return segment,
one end of said return segment being turned back at a
second interface between the central region and a
second edge region adjacent to a second lateral end or
in the vicinity thereof and the other end of said
return segment being terminated within the central
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