Pneumatic tire

Patent metadata

Field	Value
Publication number	US-10202007-B2
Application number	US-201414898196-A
Country	US
Kind code	B2
Filing date	Jun 27, 2014
Priority date	Jul 5, 2013
Publication date	Feb 12, 2019
Grant date	Feb 12, 2019

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

The invention claimed is:

1. A pneumatic tire comprising a tread portion provided with
a pair of shoulder main grooves extending continuously in the tire circumferential direction on the outermost tread edge side,
a center main groove extending continuously in the tire circumferential direction between 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 each of the shoulder main grooves and the center main groove,
wherein the middle land portion is provided with middle lateral grooves each 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,
wherein the middle lateral grooves include first middle lateral grooves extending to the center main groove and second middle lateral grooves terminating in the middle land portion, and the middle lateral grooves are each provided with a groove bottom sipe extending along the middle lateral groove and opened in the groove bottom of the middle lateral groove, and
wherein the groove bottom sipe has a width of from 0.4 to 1.0 mm and the middle lateral groove has a width of from 1.3 to 3.0 mm and a depth of from 0.6 to 1.5 mm.

2. The pneumatic tire according to claim 1 , wherein, in said middle land portion, the first middle lateral grooves and the second middle lateral grooves are provided alternately in the tire circumferential direction.

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

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

5. The pneumatic tire according to claim 1 , wherein, in said middle land portion, 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.

6. The pneumatic tire according to claim 1 , wherein a ratio W8/W3 between a width W8 in the tire axial direction of said shoulder land portion and a width W3 in the tire axial direction of said middle land portion is 1.6 to 2.0.

7. The pneumatic tire according to claim 1 , wherein said groove bottom sipe has a depth in a range from 2.5 mm to 3.5 mm.

8. The pneumatic tire according to claim 1 , wherein a ratio of said depth of the middle lateral groove to the depth of said groove bottom sipe is in a range from 0.30 to 0.40.

9. A pneumatic tire comprising
a tread portion provided with a pair of shoulder main grooves extending continuously in the tire circumferential direction on the outermost tread edge side, a center main groove extending continuously in the tire circumferential direction between 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 each of the shoulder main grooves and the center main groove,
wherein said middle land portion is provided with middle lateral grooves 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 grooves are each provided with a groove bottom sipe extending along the middle lateral groove and opened in the groove bottom of the middle lateral groove,
wherein said shoulder land portion is 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, so as to define 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, the secondary portion having a width in the tire axial direction which is 0.15 to 0.30 times the width in the tire axial direction of the shoulder land portion, and
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.

10. The pneumatic tire according to claim 9 , 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.

11. The pneumatic tire according to claim 9 , wherein said shoulder land portion is provided with a second shoulder sipe extending from the inner end in the tire axial direction of each of the shoulder lug grooves to the shoulder main groove.

12. The pneumatic tire according to claim 11 , wherein the second shoulder sipes are inclined with respect to the tire axial direction to the opposite direction to the middle lateral grooves.

13. The pneumatic tire according to claim 9 , wherein a groove width W6 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.

14. The pneumatic tire according to claim 9 , wherein the groove depth d5 of the shoulder sub groove is 0.25 to 0.50 times the groove depth d1 of the shoulder main groove.

Assignees

• Sumitomo Rubber Ind

Inventors

• Oba Ryo

Classifications

• B60C2011/0393

  Narrow ribs, i.e. having a rib width of less than 8 mm · CPC title

• B60C2011/0348

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

• B60C2011/0344

  provided at the equatorial plane · CPC title

• B60C11/125 Primary

  arranged at the groove bottom · CPC title

• B60C11/0332

  by the footprint-ground contacting area of the tyre tread · CPC title