Bridgestone Tire Company Limited

Bridgestone Corporation

Mitaka Instrument Company Limited

Takashi Takusagawa

Nobumasa Ikeda

Masao Nakamura

Akira Matsuda

Akio Sato

Norio Iwata

Akira Fujikawa

Hiroshi Hirakawa

Hiroshi Hayakawa

Shigeo Yasuda

Yuji Tateo

Kojiro Yamaguchi

Norio Goshima

Minoru Togashi

Toshio Kita

Yosuke Okado

Akira Kurima

Masaaki Kaida

Yoshiharu Goto

Nobuyuki Kasahara

Hiroshi Fujikawa

To prevent crack occurrence at groove bottoms on both side areas of foam rubber tread of all-season studless tires, the pneumatic tire having a tread surface portion composed of at least two outer and inner rubber layers is characterized in that the hardness of the inner rubber layer lies from 54 to 80 degrees in Shore hardness and is higher than that of the outer rubber layer, and further the outer rubber layer is made of foam rubber with a foam rate from 5 to 50% with at least 10% volume ratio with respect to tread volume. The outer foam rubber layer serves to improve tire performance on icy and snowy roads in winter, and the inner ordinary rubber layer serves to reduce change in groove width after vulcanization, that is, reduce dynamic strain concentration at lateral grooves and therefore to reduce crack generation at the lateral groove bottoms.

Pneumatic tire having outer tread layer of foam rubber

A pneumatic tire has plural lugs defined by plural notches in at least a tread side region. These lugs have an alternate structure of round shoulders and square shoulder between mutual adjoining lugs.

Pneumatic tires with round and square shoulders

A heavy duty low-section pneumatic and a process for manufacturing the same are disclosed. This tire comprises a radial carcass toroidally extending between bead portions, a belt composed of a first and second belt layers successively superimposed around a crown portion of the carcass and a tread rubber having substantially the same width as the maximum width of the belt. In the belt, the first belt layer is composed of at least two cord plies each containing cords inclined at a small angle with respect to the equatorial plane of the tire, the cords of which being crossed with each other with respect to the equatorial plane, while the second belt layer is composed of at least one cord ply containing non-expansible or hardly expansible cords arranged in substantially parallel to the equatorial plane and extends over both sides of the first belt layer between the first belt layer and the carcass.

Heavy duty low-section pneumatic radial tire and a process for

Heavy-duty low-section pneumatic radial tire

A pneumatic radial tire for passenger cars having a low rolling resistance and an excellent wet skid resistance is disclosed. The radial tire comprises a carcass of a radial construction toroidally extending between a pair of bead cores with the ends turned thereover, a tread portion arranged outside a crown portion of the carcass and having a two laminate structure of tread base rubber and tread cap rubber, and a reinforcing belt layer embedded in the tread base rubber and superimposed about the crown portion of the carcass. The tread base rubber and tread cap rubber have resiliences of not less than 65% and not more than 60%, respectively. The tread portion has a sectional ratio of a sectional area of the tread cap rubber occupied in the equatorial section of tire to a total sectional area of the tread portion of not less than 50% and a negative ratio of not more than 45%. The belt layer has a flatness of not more than 15%.

Pneumatic radial tires for passenger cars having low rolling resistance

A pneumatic radial tire having a reduced rolling resistance and particularly suitable for a passenger car, comprising a toroidal carcass, a belt layer, a bead core, a side rubber, a tread rubber, a relatively thin base rubber, and a rubber filler, wherein provision is made of a stress relieving groove composed of a depression facing toward the bead rubber at a position near the joint portion between the side rubber and the tread rubber, the base rubber having a resilience which is higher than those of the tread rubber and the bead rubber.

Pneumatic radial tire having a reduced rolling resistance

A pneumatic radial tire for passenger cars having a low rolling resistance is disclosed. The radial tire comprises a body reinforcement including a toroidal carcass composed of radially arranged cords and a belt superimposed about the carcass and consisting of plural rubberized plies each containing cords arranged at 60.degree.-80.degree. with respect to the radial plane of the tire, which cords of said plies being crossed with each other, and a bead reinforcement wherein the carcass is wound around a bead core to form a turnup portion, thread and sidewall rubbers covering these reinforcements. In the radial tire, a super-hard bead filler rubber is arranged at a region extending from the bead core to the middle part of the side portion, and a base rubber having a low loss modulus and a high resilience is arranged on at least both side edge parts of the belt at a volume ratio in the coating rubber for tread portion of 0.1-0.5.

Pneumatic radial tires for passenger cars having a low rolling resistance

There is described a pressure-responsive switch device particularly suitable for the detection of a pressure drop in a pneumatic tire on a vehicle wheel, wherein a contact carrying movable rod member is securely urged into a contact closing position by means of a conical compression spring to actuate a warning device whenever the internal pressure of the tire drops below a predetermined level. A permanent magnet may be mounted at the contact point of the switch to impart a quick motion thereto.

Pressure-responsive switch device for pneumatic tires

A rubber composition comprising a rubber containing a polymer of ethylene-propylene copolymer or ethylene-propylene-diene terpolymer, polybutene and an inorganic filler has an excellent puncture-sealing property. Tubeless tires provided with the rubber composition have a high resistance against the puncture.

Puncture-sealing rubber composition

A low tire pressure alarm system for pneumatic tires, wherein a radio transmitter which is adapted to produce an alarm signal of a predetermined frequency upon detection of an abnormal pressure drop is accommodated in a hollow casing for mounting on a wheel cap casing of a vehicle wheel. The alarm signal is transmitted through the hollow casing per se or through a metal coating on the hollow casing where the latter is formed from a non-conductive material. The transmitted signal is received by a receiving set which includes a receiving antenna located on the underside of the vehicle body for shielding the same from spurious or extraneous signals and a radio receiving unit mounted within a luggage compartment of signals. Upon reception of the alarm signal, the radio receiver actuates an alarming device which produces a flashing light or sound to indicate the pressure drop to an operator of the vehicle.

Growing community of inventors

Ohme, Japan

Takashi Takusagawa