Abstract: When a speech sound of at least a predetermined sound pressure is externally input while a time measurement is not being performed, a time measuring circuit starts a time measurement responsive to a signal from a speech detector. When another speech sound of at least a predetermined sound pressure is externally input while a time measurement is being performed by the time measuring circuit, a measurement time measured by the time measuring circuit at this moment is stored in a time information memory. After a predetermined time has elapsed, if a speech recognition circuit recognizes that the externally input speech sound is a "stop" command, the time measurement operation performed by the time measuring circuit is stopped, and the time information stored in the time information memory is read out and displayed as measurement time information on a display unit.

Abstract: In order to improve the wandering performance of a radial tire, that is, to increase the camber thrust, the camber torque and the self-alignment effort of the tire without degrading various performances required for the radial tire, the radial tire is formed with a plurality of main zigzag wide grooves extending in the circumferential direction of the tire; at least one auxiliary straight narrow groove disposed on the shoulder rib and extending in a circumferential direction of the tire; and a plurality of sipes arranged outside the auxiliary groove at regular intervals along the outermost circumferential edge of the tire and extending in the lateral direction of the tire from the outermost end of the tire to the auxiliary groove. The width W.sub.a of the auxiliary groove is 1 to 4% of that of the main grooves W.sub.m ; the outward inclination angle .theta..sub.

Abstract: Pneumatic tires, particularly tires for heavy load vehicles are disclosed. In the tire of this type, the tread rubber is divided into three rubber portions of central and either side regions in the direction of rotational aixs of the tire. As the material of the tread rubber, the central region uses a rubber having a good cut resistance, while the either side region uses a rubber having a good wear resistance.

Abstract: A pneumatic tire is disclosed, which comprises a carcass composed of at least one ply and an inner liner arranged inside the carcass and composed of plural rubber layers. In the tire of this type, the inner liner comprises at least three layers of an outermost layer adjacent to the carcass, an innermost layer facing the inner space of the tire and an intermediate layer interposed between the innermost and outermost layers. The innermost layer is composed of a rubber composition containing 15-60 parts by weight of natural rubber and the balance of a halogenated butyl polymer as a rubber component, while the intermediate layer is composed of a rubber composition containing only a halogenated butyl polymer as a rubber component, which is different from that of the outermost layer in the rubber component.

Abstract: Disclosed herein is a pneumatic tire comprising a carcass composed of at least one cord ply extending between a pair of bead portions, an inner liner adhered to the inner surface of the carcass, and a rubber reinforcing layer made of a rubber composition different from and having a Shore A hardness higher than that of the inner liner and disposed at a lower part of the bead portion including a bead toe portion and a bead heel portion to form an outermost bead rubber at least at that region of the bead portion which comes into contact with a rim.

Abstract: A heavy duty pneumatic radial tire exhibiting less railway wear is disclosed. This tire has a tread pattern formed in a tread divided into a plurality of circumferential ribs by at least two zigzag grooves. Each of these zigzag grooves has a width, amplitude and pitch of 4.5 to 7.5%, 0.5 to 2.0% and 2.0 to 7.0%, respectively, based on a width of the tread.

Abstract: Reinforcing structure at bead sections of radial tires for heavy load comprising(1) at least one carcass ply(2) at least one chafer(3) a circular triangular composite rubber stiffener composed of a lower half portion having a higher modulus and an upper half portion having a lower modulus, which is disposed between a case main portion and the turned-over carcass ply portion and(4) a reinforcing member composed of at least two rubberized organic fiber cord layers arranged at the case main portion, the inward end in the radial direction of said reinforcing member being locked with the bead base and said reinforcing member being disposed along a circular region having a given height at the case main portion.

Abstract: A heavy duty pneumatic radial tire comprises a tread continuous at its round-shaped shoulders with sidewalls and formed with a plurality of main tread grooves extending circumferentially thereof. The tread is formed with a circumferentially extending narrow groove in zigzag in each end zone of contact surfaces of the shoulders with a road surface under a standard load. The zigzag grooves have a width of 15-30% of that of the main tread grooves, an amplitude of 0.5-2.0% of the tread width and a pitch of 2.0-7.0% of the tread width. Each of the shoulders is formed in its side surface with a series of intermittent circumferential caved portions, such that a distance in an axial direction of the tire between the deepest bottoms of the caved portions is 105-110% of the tread width and the deepest bottoms are located in a circle having a diameter less than that of a circle passing through the bottoms of the main tread grooves.

Abstract: A heavy duty pneumatic radial tire is disclosed. This tire has a tread pattern formed in a tread divided into zigzag circumferential ribs by at least two zigzag main grooves. The tread includes a stress-mitigating rib arranged at least near the top of the convex part of the circumferential rib and parallel to the edge line of the circumferential rib through substantially an isolation groove.

Abstract: A reinforced construction of bead portions of radial tires for heavy load vehicles such as trucks, buses etc., which is well balanced in rigidity and which has an excellent durability is disclosed. The construction includes a first reinforcing layer and a second reinforcing layer, the first reinforcing layer being substantially continuously extended from a height covering both the upper ends of the second reinforcing layer and of the turned-up portion of the carcass ply to the inside surface of the carcass ply, the second reinforcing layer being interposed between the turned-up portion of the carcass ply and the first reinforcing layer, the axially inside portion of said first reinforcing layer which is disposed along the inside of the carcass ply having an upper end whose height h.sub.1 from the bead base portion is given byh.sub.1 =(0.8 to 2.5)h.sub.0where h.sub.