# US 9,751,366 B2 · Pneumatic tire

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- Number: US 9,751,366 B2
- Document ID: US9751366B2
- Status: Granted
- Kind: B2
- Application number: 14/058,491
- Filed: 2013-10-21
- Published: 2014-06-05
- Granted: 2017-09-05
- Earliest claimed: 2012-12-03
- Assignees: Toyo Tire & Rubber Co., Ltd.
- Applicants: Toyo Tire & Rubber Co., Ltd.
- Inventors: Kenichi Yamashita
- Web page: https://patentgrep.com/patent/US9751366B2

## CPC

- B60C 11/1346: {covered by a rubber different from the tread rubber}
- B60C 11/005: {with cap and base layers}
- B60C 11/0058: {with different cap rubber layers in the axial direction}
- B60C 2011/0025: {Modulus or tan delta}
- Y02T 10/86: Optimisation of rolling resistance, e.g. weight reduction
- B60C: VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

The invention provides a pneumatic tire which can reduce a rolling resistance while maintaining an wear resistance. Among a cap portion in a center area, at least the cap portion of a center land portion is provided with a cap front layer which includes a surface, and a cap inner layer which is laminated in an inner periphery of the cap front layer. A loss tangent of the cap front layer is set to be smaller than a loss tangent of the cap inner layer and be smaller than a loss tangent of the cap portions in the shoulder areas.

## Claims

### Claim 1

A pneumatic tire comprising:
a tread rubber; and
a plurality of main grooves extending along a tire peripheral direction and provided in the tread rubber,
wherein the tread rubber has a center area which is arranged between a pair of outer main grooves arranged in an outermost side in a tire width direction, and a pair of shoulder areas which are arranged in outer sides in the tire width direction of the outer main grooves,
wherein the center area has at least one center land portion which is zoned by the main grooves and is positioned in a center portion in the tire width direction,
wherein the tread rubber has a cap portion which constructs an outer layer, and a base portion which is laminated in an inner periphery of the cap portion and constructs an inner layer,
wherein at least the cap portion of at least one center land portion among the cap portion in the center area has a cap front layer which includes a surface, and a cap inner layer which is laminated in an inner periphery of the cap front layer, the cap front layer has a surface portion which is arranged along the surface of the cap portion, wherein each cap portion of the pair of shoulder areas is constructed as a single layer,
wherein the cap front layer further comprises a groove wall portion which is arranged so as to extend along a wall portion of the main grooves from the surface portion, the groove wall portion is arranged so as to extend to a bottom portion of the main grooves from an inner edge of the main grooves, and further, extend at least to a position of an inner peripheral surface in the tire diametrical direction of the surface portion along an outer wall portion of the main grooves from the bottom portion of the main grooves, and so as not to extend to an outer edge of the main grooves,
wherein a loss tangent of the cap front layer is set to be smaller than a loss tangent of the cap inner layer and be smaller than a loss tangent of the cap portions in the shoulder areas, and
wherein a thickness of the surface portion is set to be less than one third a depth of the main grooves
wherein the center area having at least one center land portion positioned in the center portion in the tire width direction further comprises a first mediate land portion and a second mediate land portion which are arranged on either side of the at least one center land portion in the tire width direction, and
wherein the cap portion in the at least one center land portion is constructed by a multilayer comprising the cap front layer and the cap inner layer, and the cap portion in the first mediate land portion and the second mediate land portion is constructed by a single layer.

### Claim 2 (depends on 1)

The pneumatic tire according to claim 1, wherein each cap portion of the pair of shoulder areas is constructed by a same rubber material as the cap inner layer in the cap portion of the at least one center land portion.

### Claim 3 (depends on 1)

The pneumatic tire according to claim 1, wherein the cap portion in the first mediate land portion and the second mediate land portion is constructed by a same rubber material as the cap inner layer in the at least one center land portion.

### Claim 4 (depends on 1)

The pneumatic tire according to claim 1, further comprising a carcass layer constructed by a ply and a belt layer arranged in an outer periphery of the carcass layer.

### Claim 5 (depends on 1)

The pneumatic tire according to claim 1, wherein the thickness of the surface portion is set to be equal to or less than 15% the depth of the main grooves.