Bridgestone Corporation

Bridgestone Tire Company Limited

Railway Technical Research Institute

Masahiro Kuroda

Hiroshi Ueda

Michio Ishii

Naoyuki Goto

Toyomi Iwata

Shohachiro Nakayama

Minoru Togashi

Kazuhiro Oda

Hideyuki Takizawa

Takeshi Takanami

Yukimasa Yamada

Masayoshi Azakami

Yasushi Sumikawa

Hisao Seitoh

A precure tread for a tire has surface grooves facing a tread face, rear grooves facing a crown portion of a base tire, and a passage for communication between the rear grooves to atmosphere. The groove bottom of the rear grooves is located at a higher level than a groove bottom of the surface groove in the radial direction. The tire durability can be considerably improved when this precure tread is applied to a new tire or a retreaded tire.

Precure tread for retread tire

A precure tread for a tire has surface grooves facing a tread face, rear grooves facing a crown portion of a base tire, and a passage for communication between the grooves to atmosphere. The groove bottom of the rear grooves is located at a high level than a groove bottom of the surface groove in the radial direction. The tire durability can be considerably improved when this precure tread is applied to a new tire or a retreated tire.

Precure tread for tire including surface and rear grooves

A precure tread for a tire has surface grooves facing a tread face, rear grooves facing a crown portion of a base tire, and a passage for communication between the rear grooves to atmosphere. The groove bottom of the rear grooves is located at a higher level than a groove bottom of the surface groove in the radial direction. The tire durability can be considerably improved when this precure tread is applied to a new tire or a retread tire.

Precure tread for a new tire, and retread tires

In a tire for a levitation-type vehicle for supporting a load which varies depending upon a change in speed of the levitation-type vehicle at landing and during subsequent traveling thereof, a configuration of a crown and rigidity of the crown are set so as to have a ground-contact configuration in which, when a load of the levitation-type vehicle is equal to or less than 45% at its full load, a ratio of a ground-contact length of a pair of shoulders in a circumferential direction of the tire with respect to a ground-contact length, in the circumferential direction of the tire, of a central portion of the crown in the widthwise direction is 0.6.about.1.5. Accordingly, the tire for the levitation-type vehicle has a wide ground-contact area at an initial stage of landing and traveling.

Radial tire for levitation-type vehicle

A bias tire for an aircraft includes a laminate formed by laminating a plurality of plies intersecting with each other and reinforced by organic fiber cords having a large thermal contraction coefficient. Both ends of the plies are turned up around bead cores. A profile curve I of a representative ply corresponding to that number counted from an innermost ply of the laminate plus one, which is one half of a total number of the plies when the tire mounted on a normal rim is filled with 1% of a normal inner pressure is constructed by a smoothly changing crown profile curve J and a smoothly changing side profile curves K. The crown profile curve J intersects a natural equilibrium profile curve H and is positioned between natural equilibrium profile curves E and H between both shoulder ends. The side profile curves K contact both the natural equilibrium profile curves E and H at rim points and smoothly connecting with the crown profile curve J and are positioned outwardly of the natural equilibrium profile curves E and H between the shoulder ends and rim points.

Bias tire for aircraft

A tread pattern of two main groove-rib type provided with auxiliary grooves having excellent stone-biting resistance and stone-expelling property is disclosed. In the tread pattern, a pair of main grooves are disposed near both side edges of the tread along these edges and one or two pairs of auxiliary grooves are oppositely arranged between the main grooves, wherein the bottom of the auxiliary groove is directed to the center of the tire in such a manner that the center line in radial section of the auxiliary groove is inclined at an angle of 5.degree.-20.degree. with respect to a normal line of the tread drawn from an intersection of the center line and the tread.

Two main groove-rib type tread pattern

A pneumatic tire for a high speed under a heavy load is disclosed. In order to effectively refrain a crown radius of curvature of the tire from decreasing due to a centrifugal force, the tire is constructed as follows. The tire comprises a case reinforcing layer composed of a plurality of carcass plies mainly formed of organic textile cords inclined at an angle of at most 45.degree. to the circumferential direction of the tire and a plurality of reinforcing fabrics whose material and inclined angle to the circumferential direction of the tire are substantially the same as those of the cords of the carcass ply and interposed between the carcass plies. The plurality of reinforcing fabrics extend from those positions which are distant apart from one of bead portions through a tire crown portion and terminating at those positions which are distant apart from the other bead portion. The number of the reinforcing fabrics is at least 20% of the total number of both the carcass plies and the reinforcing fabrics. The total number of the case reinforcing layers is divided into two halves and one of the two halves cross the other halves. The reinforcing fabrics are gradually changing in width within a range between 35% and 60% of the inner peripheral length of the tire and symmetrically arranged with respect to a crown center portion.

Pneumatic tire for high speed under heavy load

A reinforced bead portion for pneumatic tires used under heavy load and high flexural conditions, which can efficiently alleviate the stress subjected to a pair of bead cores each composed of at least two bead cores is disclosed. At least the inside bead core of the reinforced bead portion comprises a sector-shaped stress absorbing rubber layer included between two straight radial lines diverging from a center of the bead core, one of the these straight lines being inclined at an angle of 120.degree. to 135.degree. with respect to the other line. The stress absorbing rubber layer has a maximum thickness at its center which is 0.7 to 6, preferably 1 to 2.5 times the diameter of a metal cord of the bead core and a hardness which is at least equal to that hardness of a coating rubber of either one of a rubberized metal cord layer and a rubberized fabric for covering the rubberized metal cord layers which is lower than the hardness of the other.

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Higashimurayama, Japan

Masahiro Kuroda