Pneumatic tire

Patent metadata

Field	Value
Publication number	US-9757991-B2
Application number	US-201414170743-A
Country	US
Kind code	B2
Filing date	Feb 3, 2014
Priority date	Feb 19, 2013
Publication date	Sep 12, 2017
Grant date	Sep 12, 2017

Abstract

A pneumatic tire is provided in the tread portion with a central land portion between two crown main grooves. The central land portion is provided with notches each having a depth of 55% to 65% of the depth of the crown main groove and having a closed end and an open end opening to the crown main groove.
The maximum axial length of the central notch is 10% to 15% of the maximum axial length of the central land portion, and the circumferential length of the opening is 10% to 15% of one circumferential pitch of the shoulder block row 7 R.
The circumferential length of the opening is 15% to 25% of one circumferential pitch of the central notches.

First claim

The invention claimed is:

1. A pneumatic tire comprising a tread portion provided with
a crown main groove extending continuously in the tire circumferential direction and disposed on each side the tire equator,
a shoulder main groove extending continuously in the tire circumferential direction and disposed axially outside each said crown main groove,
a plurality of middle axial grooves extending between said crown main groove and said shoulder main groove, and
a plurality of shoulder axial grooves extending between said shoulder main groove and the adjacent tread edge so that the tread portion is divided into
a row of circumferentially arranged shoulder blocks formed between said shoulder main groove and said tread edge,
a single row of circumferentially arranged middle blocks formed between said crown main groove and said shoulder main groove, and
a single central land portion formed between the two crown main grooves and disposed on the tire equator,

wherein
the central land portion is provided with central notches extending from the two crown main grooves toward the tire equator, and terminating within the central land portion so that the central land portion extends continuously in the tire circumferential direction, wherein
the depth of each said central notch is in a range of from 55% to 65% of the depth of the adjacent crown main groove,
said central notches satisfy the following condition:
the maximum axial length of each said central notch is 10% to 15% of the maximum axial length of the central land portion, and the circumferential length of an opening of each said central notch to the crown main groove is 10% to 15% of one pitch of the shoulder blocks in said row of shoulder blocks,
each said crown main groove is a zigzag groove composed of alternate long groove segments and short groove segments,
each said shoulder main groove is a zigzag groove composed of alternate long groove segments and short groove segments, and
each said middle block is provided with notches which are
an axially inside notch formed adjacently to the crown main groove so as to include one of intersections between the long groove segments and the short groove segments of the crown main groove, and
an axially outside notch formed adjacently to the shoulder main groove so as to include one of intersections between the long groove segments and the short groove segments of the shoulder main groove.

2. The pneumatic tire according to claim 1 , wherein each said central notch has, in its top view, a polygonal shape defined by four or more sides.

3. The pneumatic tire according to claim 2 , wherein each said central notch is formed so as to include one of intersections between the long groove segments and the short groove segments of the adjacent crown main groove.

4. The pneumatic tire according to claim 2 wherein the ratio of the ground contacting area of the tread portion to the overall area of the tread portion is 68% to 72%.

5. The pneumatic tire according to claim 1 , wherein each said central notch is formed so as to include one of intersections between the long groove segments and the short groove segments of the adjacent crown main groove.

6. The pneumatic tire according to claim 5 , wherein
the central land portion has an edge being adjacent to each of the crown main grooves and comprising long central edge segments extending along the long groove segments of the crown main groove and short central edge segments extending between the long central edge segments,
the middle blocks have axially inner middle block edges being adjacent to the respective crown main grooves and comprising short middle block edge segments and long middle block edge segments between the short middle block edge segments,
the short middle block edge segments are inclined with respect to the tire circumferential direction in one direction,
the long middle block edge segments are inclined with respect to the tire circumferential direction in one direction opposite to that of the short middle block edge segments, and have a circumferential length longer than the circumferential length of the short middle block edge segments,
on both sides of each of the crown main grooves, the short central edge segments are overlapped with the short middle block edge segments in the tire circumferential direction, and
an arrangement pitch of the short central edge segments is the same as an arrangement pitch of the short middle block edge segments.

7. The pneumatic tire according to claim 5 , wherein the ratio of the ground contacting area of the tread portion to the overall area of the tread portion is 68% to 72%.

8. The pneumatic tire according to claim 1 , wherein the ratio of the ground contacting area of the tread portion to the overall area of the tread portion is 68% to 72%.

9. The pneumatic tire according to claim 8 , wherein
the central land portion has an edge being adjacent to each of the crown main grooves and comprising long central edge segments extending along the long groove segments of the crown main groove and short central edge segments extending between the long central edge segments,
the middle blocks have axially inner middle block edges being adjacent to the respective crown main grooves and comprising short middle block edge segments and long middle block edge segments between the short middle block edge segments,
the short middle block edge segments are inclined with respect to the tire circumferential direction in one direction,
the long middle block edge segments are inclined with respect to the tire circumferential direction in one direction opposite to that of the short middle block edge segments, and have a circumferential length longer than the circumferential length of the short middle block edge segments,
on both sides of each of the crown main grooves, the short central edge segments are overlapped with the short middle block edge segments in the tire circumferential direction, and
an arrangement pitch of the short central edge segments is the same as an arrangement pitch of the short middle block edge segments.

10. The pneumatic tire according to claim 1 , wherein
the shoulder blocks in said row have axially inner edges comprising:
a plurality of long shoulder block edges inclining with respect to the tire circumferential direction in one direction, and
a plurality of short shoulder block edges which are opening edges of the shoulder axial grooves between the long shoulder block edges.

11. A pneumatic tire comprising a tread portion provided with
a crown main groove extending continuously in the tire circumferential direction and disposed on each side the tire equator,
a shoulder main groove extending continuously in the tire circumferential direction and disposed axially outside each said crown main groove,
a plurality of middle axial grooves extending between said crown main groove and said shoulder main groove, and
a plurality of shoulder axial grooves extending between said shoulder main groove and the adjacent tread edge

so that the tread portion is divided into
a row of circumferentially arranged shoulder blocks formed between said shoulder main groove and said tread edge,
a single row of circumferentially arranged middle blocks formed between said crown main groove and said shoulder main groove, and
a single central land portion formed between the two crown main grooves and disposed on the tire equator,

wherein
the central land portion is provided with central notches extending from the two crown main grooves toward the tire equator, and terminating within the central land portion so that the central land portion extends continuously in t

Assignees

• Sumitomo Rubber Ind

Inventors

• Tagashira Masao
• Nakayama Hiroyuki

Classifications

• B60C11/0304

  Asymmetric patterns · CPC title

• B60C11/1259 Primary

  Depth of the sipe · CPC title

• B60C2011/0348

  Narrow grooves, i.e. having a width of less than 4 mm · CPC title

• B60C2011/0355

  characterised by depth · CPC title

• B60C2011/1209

  straight at the tread surface · CPC title