# US 2014/0150944 A1 · Pneumatic tire

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- Number: US 2014/0150944 A1
- Document ID: US20140150944A1
- Status: Published application
- Kind: A1
- Application number: 14/058,491
- Filed: 2013-10-21
- Published: 2014-06-05
- 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/US20140150944A1

## 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 groove,
wherein the center area has a center land portion which is zoned by the main groove 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 the 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, and
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.

### Claim 2 (depends on 1)

The pneumatic tire according to claim 1, wherein the cap front layer has a surface portion which is arranged along the surface of the cap portion.

### Claim 3 (depends on 2)

The pneumatic tire according to claim 2, wherein a thickness of the surface portion is set to be less than one third a depth of the main groove.

### Claim 4 (depends on 2)

The pneumatic tire according to claim 2, 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 groove from the surface portion.

### Claim 5 (depends on 3)

The pneumatic tire according to claim 3, 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 groove from the surface portion.