The Yokohama Rubber Co., Ltd.

Motohide Takasugi

Masaki Noro

Ryoji Hanada

Yukimasa Minami

Masatoshi Kuwajima

Naoya Amino

Hikomitsu Noji

Kazuyoshi Saneto

Eiichi Iida

Naoyuki Katsura

A pneumatic tire for an automobile having a tread portion in a two-layered structure of a cap tread layer and an under tread layer, in which the under tread layer is constituted by a center region defined by a range of 30 through 70% of a width of a first belt layer and up to 0.5 through 2.0 mm in a tire diameter direction from a second belt layer and a shoulder region extended from both end portions of the first belt layer continuously from the center region to an outer side by 30 mm at maximum on one side and having a thickness of 1.0 through 5.0 mm, the regions comprising rubber composition members different from each other, the center region is arranged with a rubber layer where JIS-A hardness falls in a range of 65 through 80 and an amount of blending a softening agent relative to rubber 100 weight parts is smaller than that of the cap tread layer by 10 weight parts or more, the shoulder region is arranged with a rubber layer where JIS-A hardness falls in a range of 50 through 70 and the amount of blending the softening agent relative to rubber 100 weight parts is smaller than that of the cap tread layer by 10 weight parts or more and a ratio (tan &dgr; /tan &dgr; ) of loss tangent (tan &dgr; ) of the rubber layer of the shoulder region to loss tangent (tan &dgr; ) of the rubber layer of the center region is 2/3 or smaller.

Pneumatic tire for automobile and its fabrication method

Pneumatic tire and pneumatic tire set

In a pneumatic tire having an asymmetric tread pattern in witch ribs continuing in a tire circumferential direction are disposed on a tread surface at a shoulder end portion on the outer side of a vehicle when the tire is fitted to the vehicle, and block lines each comprising a plurality of blocks are disposed at a shoulder end portion on the inner side of the vehicle, wherein sub-grooves extending in a tire width-wise direction while forming right and left pairs are disposed on the portion of the tire more inward than the ribs at a predetermined pitch in the tire circumferential direction and in a herringbone pattern widening in a direction opposite to a rotating direction of the tire, the apexes of the herringbone patterns are positioned on the outer side of the tire with respect to a tire equator line, and pairs of the right and left sub-grooves are made mutually discontinuous at the apexes.

Pneumatic tire having asymmetric tread pattern

A pneumatic radial tire for a passenger vehicle, characterized in that at least a portion of a carcass line extending radially outwardly from the maximum width position in a carcass line of a tire fitted to a normal rim and inflated up to its normal internal pressure is configured so as to substantially conform to an equilibrium carcass line expressed by the following equations (1) and (2) calculated by using an internal pressure allotment ratio g(y) of a carcass layer at the tread portion that is obtained by setting the distributional configuration index .alpha. of the following equation (3) at 4 or more, and that a tread pattern having a directional property is provided to the tread surface thereof, wherein: ##EQU1## wherein, provided that a line drawn vertically downwardly from the center of the tread portion to the axle of the tire is y axis of coordinates with the axle of the tire being z axis of coordinates, y.sub.A, y.sub.D, y.sub.C, y.sub.B and .eta. denote as follows:

Pneumatic radial tire for passenger vehicle including a particular

A pneumatic radial tire for a passenger vehicle, characterized in that at least a portion of a carcass line extending radially outwardly from the maximum width position in a carcass line of a tire fitted to a normal rim and inflated up to its normal internal pressure is configured so as to substantially conform to an equilibrium carcass line expressed by the following equations (1) and (2) calculated by using an internal pressure allotment ratio g(y) of a carcass layer at the tread portion that is obtained by setting the distributional configuration index .alpha. of the following equation (3) at 4 or more, and that the width of the belt layer extending radially outwardly of the tire is made to range from 105 to 120% of the ground-contacting width of the tread portion when loaded with a designed normal load, wherein: ##EQU1## wherein, provided that a line drawn vertically downwardly from the center of the tread portion to the axle of the tire is y axis of coordinates with the axle of the tire being z axis of coordinates, yA, yD, yC, yB and .eta. denote as follows:

Pneumatic radial tire for passenger vehicle with specified carcass

A pneumatic radial tire for a passenger vehicle, characterized in that at least a portion of a carcass line extending radially outwardly from the maximum width position in a carcass line of a tire fitted to a normal rim and inflated up to its normal internal pressure is configured so as to substantially conform to an equilibrium carcass line expressed by the following equations (1) and (2) calculated by using an internal pressure allotment ratio g(y) of a carcass layer at the tread portion that is obtained by setting the distributional configuration index .alpha. of the following equation (3) at 4 or more, and that grooves are provided in the tread surface such that the groove area ratio thereof ranges from 20 to 30%, wherein: ##EQU1## wherein, provided that a line drawn vertically downwardly from the center of the tread portion to the axle of the tire is y axis of coordinates with the axle of the tire being z axis of coordinates, y.sub.A, y.sub.D, y.sub.C, y.sub.B and .eta. denote as follows:

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Hiratsuka, Japan

Motohide Takasugi