Pneumatic tire

Patent metadata

Field	Value
Publication number	US-2016144668-A1
Application number	US-201414898196-A
Country	US
Kind code	A1
Filing date	Jun 27, 2014
Priority date	Jul 5, 2013
Publication date	May 26, 2016
Grant date	—

Abstract

To provide a pneumatic tire which is improved in on-snow performance, while maintaining steering stability on dry road surface. The pneumatic tire is provided in a tread portion 2 with a pair of shoulder main grooves 3 , a center main groove 4 , shoulder land portions 6 , and middle land portions 5 . The middle land portions 5 are provided with middle lateral grooves 10 extending from the shoulder main grooves 3 toward the inside in the tire axial direction, while gradually decreasing the angle with respect to tire circumferential direction. The middle lateral groove 10 is provided with a groove bottom sipe 15 opened in the groove bottom.

First claim

1 . A pneumatic tire provided in the tread portion with
a pair of shoulder main grooves extending continuously in the tire circumferential direction on the most tread edge side, a center main groove extending continuously in the tire circumferential direction on the inner side in the tire axial direction of the shoulder main grooves, a shoulder land portion on the outer side in the tire axial direction of each of the shoulder main grooves, and a middle land portion between the shoulder main groove and the center main groove, and characterized in that the middle land portion is provided with a middle lateral groove extending from the shoulder main groove toward the inside in the tire axial direction, while decreasing the angle with respect to the tire circumferential direction, and the middle lateral groove is provided with a groove bottom sipe extending along the middle lateral groove and opened in the groove bottom of the middle lateral groove.

2 . The pneumatic tire according to claim 1 , wherein
the groove depth of the middle lateral groove is 0.6 to 1.5 mm.

3 . The pneumatic tire according claim 1 , wherein
the middle lateral groove includes a first middle lateral groove extending to the center main groove and a second middle lateral groove terminating in the middle land portion.

4 . The pneumatic tire according to claim 3 , wherein
the first middle lateral groove and the second middle lateral groove are provided alternately in the tire circumferential direction.

5 . The pneumatic tire according to claim 1 , wherein the angle of the middle lateral groove with respect to the tire circumferential direction is 40 to 60 degrees.

6 . The pneumatic tire according to claim 1 , wherein the groove width of the middle lateral groove is 1.3 to 3.0 mm.

7 . The pneumatic tire according to claim 1 , wherein the width of the groove bottom sipe is 0.4 to 1.0 mm.

8 . The pneumatic tire according to claim 1 , wherein a ratio Sr/Sv between an actual ground contacting area Sr of the middle land portion and a virtual ground contacting area Sv of the middle land portion measured in such a state that all grooves provided in the middle land portion are filled is 0.80 to 0.90.

9 . The pneumatic tire according to claim 1 , wherein a ratio W 8 /W 3 between a width W 8 in the tire axial direction of the shoulder land portion and a width W 3 in the tire axial direction of the middle land portion is 1.6 to 2.0.

10 . The pneumatic tire according to claim 1 , wherein, by being provided with a shoulder sub groove extending continuously in the tire circumferential direction and having a smaller groove width than that of the shoulder main groove,
the shoulder land portion includes a main portion on the outside in the tire axial direction of the shoulder sub groove and a secondary portion between the shoulder sub groove and the shoulder main groove, and a ratio W 7 /W 8 between a width W 7 in the tire axial direction of the secondary portion and the width W 8 in the tire axial direction of the shoulder land portion is 0.15 to 0.30.

11 . The pneumatic tire according to claim 10 wherein
the main portion is provided with a plurality of shoulder lug grooves extending from a tread edge toward the inside in the tire axial direction and terminating without being communicated with the shoulder sub groove.

12 . The pneumatic tire according to claim 10 , wherein
the main portion is provided with a first shoulder sipe of which inner end in the tire axial direction terminates within the main portion.

13 . The pneumatic tire according to claim 11 , wherein
the shoulder land portion is provided with a second shoulder sipe extending from the inner end in the tire axial direction of the shoulder lug groove to the shoulder main groove.

14 . The pneumatic tire according to claim 13 , wherein
the second shoulder sipes are inclined with respect to the tire axial direction to the opposite direction to the middle lateral groove

15 . The pneumatic tire according to claim 10 , wherein a groove width W 6 of the shoulder sub groove is 1.3% to 2.7% of a tread width TW which is the distance in the tire axial direction between the tread edges.

16 . The pneumatic tire according to claim 10 , wherein the groove depth d 5 of the shoulder sub groove is 0.25 to 0.50 times the groove depth d 1 of the shoulder main groove.

17 . The pneumatic tire according claim 2 , wherein
the middle lateral groove includes a first middle lateral groove extending to the center main groove and a second middle lateral groove terminating in the middle land portion.

18 . The pneumatic tire according to claim 2 , wherein the angle of the middle lateral groove with respect to the tire circumferential direction is 40 to 60 degrees.

19 . The pneumatic tire according to claim 3 , wherein the angle of the middle lateral groove with respect to the tire circumferential direction is 40 to 60 degrees.

20 . The pneumatic tire according to claim 4 , wherein the angle of the middle lateral groove with respect to the tire circumferential direction is 40 to 60 degrees.

Assignees

• Sumitomo Rubber Ind

Inventors

• Oba Ryo

Classifications

• B60C2011/0353

  characterised by width · CPC title

• B60C11/125 Primary

  arranged at the groove bottom · CPC title

• B60C11/1272

  Width of the sipe · CPC title

• B60C2011/0334

  Stiffness · CPC title

• B60C11/1236

  with special arrangements in the tread pattern · CPC title