Abstract: There is provided a pneumatic tire in which a belt reinforcement layer is placed and capable of increasing both riding comfort and steering stability. Circumferential bending rigidity of a contact belt ply 25 placed in contact with the belt reinforcement layer 35 is made higher than circumferential bending rigidity of a remote belt ply 24, and thus the belt reinforcement layer 35 having high circumferential bending rigidity and the contact belt ply 25 having next high circumferential bending rigidity are collected near a neutral axis of bending positioned near a boundary thereof. Thus, composite circumferential bending rigidity of the belt layer 23 and the belt reinforcement layer 35 is reduced to reduce a vertical spring constant of the pneumatic tire 11 and increase a ground contact length.

Abstract: In a pneumatic tire for a motorcycle where grooves 30, 31 (inclined portion 32) extending generally in a width direction are formed on an outer surface of a tread portion 13 and a rotational direction is designated, driving performance or braking performance is improved. Driving force affects on a tire for a rear wheel during accelerated running, so that an entire land portion 35 between the inclined portions 32 is about to lean backwardly in the rotational direction. However, the inclined portion 32 is generally inclined forwardly in the rotational direction from a deepest point D toward an opening end K, so that a support portion 36 formed at a rear end of each land portion 35 in the rotational direction and having a substantially triangular shape strongly resists the leaning, thereby effectively suppressing the leaning of each land portion 35. As a result, grip force during driving is improved, thereby improving driving performance.

Abstract: The object of the present invention is to provide a pneumatic tire in which the durability is improved, even when organic fiber cords are used for a folded belt layer, by dispersing or reducing the compress force applied to the organic fiber cord at the both end portions of the folded belt layer. A pneumatic tire 1 has a toroidal carcass 3 and a belt 7 consisting of belt layers 5, 6 arranged in the outer circumferential side of a crown portion 4 of the carcass 3. Between the adjacent belt layers 5, 6, the cords 8, 9 are crossed with each other with respect to an equatorial plane E of the tire to form cross belt layers. The widest belt layer 6 is a folded belt layer having a body portion 10 and a folded portion 12. A cord 9 constituting the folded belt layer 6 is an organic fiber cord. A narrow belt reinforcing layer 14 of rubberized cords 13 is arranged at least immediately below the width terminal end 11 of the body portion 10 of the folded belt layer 6 which terminal end 11 abuts on the folded portion 12.

Abstract: The ride comfort and driving performance of a pneumatic tire 11 are improved while maintaining the high-speed durability and steering stability, in which an inclination angle A of steel cords 26, 27 in all belt plies 24, 25 constituting a belt layer 23 is not less than 45° with respect to an equator S of the tire, and a belt reinforcing layer 35 embedded with reinforcing cords substantially in parallel to the equator S is arranged between a belt layer 23 and a carcass layer 18, whereby an out-of-plane bending rigidity of the belt layer 23 in a circumferential direction can be lowered to make a longitudinal spring constant of the pneumatic tire 11 and uniformize the diameter of the belt reinforcing layer 35, and further a deformation amount of a tread portion 15 having a high bending rigidity can be made small.

Abstract: The present invention provides a pneumatic tire that has a tire structure modified to reduce the road noise and thereby reduce the car interior noise and that exhibits improved high-speed drivability and improved high-speed durability. The pneumatic tire includes a circular tread, a pair of sidewalls and beads on both sides of the tread, and a carcass extending between bead cores within the pair of beads. A rubber layer having a modulus of elasticity at 100% elongation in the range of 1.0 MPa to 30 MPa and a thickness in the range of 2.0 mm to 5.0 mm is placed inside the carcass and at at least part of a portion around the center of the tread.

Abstract: The ground contact pressure on land portions 44 is uniformed so that drivability is improved and uneven wear is suppressed to improve wear resistance. The parts of the carcass layer 28 and belt layer 33 overlapping with the main grooves 42 are convexly curved toward the outside in the radial direction due to the internal pressure. The reinforcing layer 49 is arranged at the position spaced from the neutral axis of deformation in the compressed side in a certain distance, i.e. radially inside of the radially outermost carcass ply 30, and the steel cords 47 which extend in the direction including the tire width direction and its approximate direction and which act as supports for resisting against the compression force are embedded in the reinforcing layer. As a result, the above-mentioned curved deformation can be effectively suppressed.

Abstract: Auxiliary grooves 28 are formed in land portions 26 so that the wet performance is improved by the increase in the edge factors of the auxiliary grooves 28 and by the water absorbing actions of the auxiliary grooves 28. Since the auxiliary grooves 28 are arranged on the shorter diagonal lines of the land portions 26, the land portions 26 are divided into two triangles approximating equilateral triangles so that the reduction, as caused by providing the auxiliary grooves 28, of the rigidity of the land portions 26 can be suppressed to the minimum. As a result, the deformation of the land portions 26 is suppressed to maintain the dry performance.

Abstract: A pneumatic tire in which a block formed in a tread surface has, in a ground contacting surface thereof, a closed sipe which is formed so as to not open onto a groove. The sipe has a first opening formed in the ground-contacting surface of the block, a second opening formed at side surfaces of the block, and a hole which communicates the first opening and the second opening. In accordance with this structure, water taken-in into the sipe from the first opening at the ground-contacting surface of the block is discharged to the second opening contacting at the side surface facing to the groove. As a result, water drainability of the sipe is improved without lowering rigidity of the block. Thus, a ground contacting performance of the block improves. The pneumatic tire therefore has improved performance on wet roads and improved performance on snowy and icy roads without the rigidity of blocks decreasing.

Abstract: A pneumatic tire. A central circumferential main groove is disposed to extend along a tire circumferential direction, along a ground contact center line of tread of the pneumatic tire. Inboard side circumferential main grooves and inboard side lateral main grooves, which are continuous with the central circumferential main groove, are provided at an inboard side of the ground contact center line. Outboard side lateral main grooves, which are continuous with the central circumferential main groove, and outboard side slanted longitudinal main grooves, which are continuous with the outboard side lateral main grooves, are disposed at an outboard side of the ground contact center line. Thus, irregular wear of land portions is continuously suppressed and controlling stability is improved. Moreover, water at the ground contact center line, which water is difficult to drain, can be efficiently drained from the ground contact area due to less water resistance.

Abstract: In a pneumatic tire of the present invention, a pair of circumferential main grooves with a tire equatorial plane interposed therebetween, and another pair of circumferential main grooves at a tire axial direction outer side and inner side of the former pair of circumferential main grooves, are provided in a central area of a tread. A groove width center line of the circumferential main grooves at the tire axial direction outermost side and innermost side is disposed at a position 30% to 40% of a ground contact half width distanced from the tire equatorial plane. Further, outboard side slanted longitudinal main grooves, and slanted lateral main grooves having ends which open into at least one of the circumferential main grooves and other ends which open into contact ground end in the vehicle width direction, are disposed on the tread.

Abstract: A method of designing a tire which takes into consideration actual conditions in the presence of a fluid, such as drainage performance, on-snow performance, noise performance, and the like. A tire model and a fluid model including the shape, structure, and the like are constructed, and a road surface condition is inputted (steps 100 to 106). Boundary conditions during tire rolling or tire nonrolling are set (step 108), deformation calculation and fluid calculation of the tire model are performed (steps 110 to 114), and a boundary surface between the tire model and the fluid model is recognized to update the boundary conditions (steps 118 and 120). The result of calculation is outputted as the result of estimation, and based on this result of estimation, main travel paths of the fluid, i.e.

Abstract: When a single performance or a plurality of antinomical performances are to be achieved, the best mode of a tire is designed under a given constraint condition. Each of blocks included in two pitch groups designated in a pitch array is modeled (100), an objective function representing a tire performance evaluation physical amount, a constraint condition for restricting a tire shape, and a design variable which is an angle of a wall surface determining each of block shapes are determined (102). Next, the design variable is varied continuously by &Dgr;ri to determine a modified model (104 to 108). A value of the objective function of the modified model and a value of the constraint condition are calculated, and a sensitivity of the objective function and a sensitivity of the constraint condition are determined (110, 112).

Abstract: A pneumatic tire in which a block formed in a tread surface has, in a ground contacting surface thereof, a closed sipe which is formed so as to not open onto a groove. The sipe has a first opening formed in the ground-contacting surface of the block, a second opening formed at side surfaces of the block, and a hole which communicates the first opening and the second opening. In accordance with this structure, water taken-in into the sipe from the first opening at the ground-contacting surface of the block is discharged to the second opening contacting at the side surface facing to the groove. As a result, water drainability of the sipe is improved without lowering rigidity of the block. Thus, a ground contacting performance of the block improves. The pneumatic tire therefore has improved performance on wet roads and improved performance on snowy and icy roads without the rigidity of blocks decreasing.

Abstract: When a single performance or a plurality of antinomical performances are to be achieved, the best mode of a tire is designed under a given constraint condition. Each of blocks included in two pitch groups designated in a pitch array is modeled (100), an objective function representing a tire performance evaluation physical amount, a constraint condition for restricting a tire shape, and a design variable which is an angle of a wall surface determining each of block shapes are determined (102). Next, the design variable is varied continuously by &Dgr;ri to determine a modified model (104 to 108). A value of the objective function of the modified model and a value of the constraint condition are calculated, and a sensitivity of the objective function and a sensitivity of the constraint condition are determined (110, 112).

Abstract: When a single performance or a plurality of antinomical performances are to be obtained, the best mode of a tire is designed under a given condition. A basic shape model using one block as a reference shape is obtained (100). An object function representing a tire performance evaluation physical amount, a constraint condition for restricting the tire shape, and a design variable which is an angle of a wall surface which determines the block shape are determined (102). Next, the design variable is varied continuously by &Dgr;ri to determine a modified shape model (104 to 108). A value of the object function of the modified shape model and a value of the constraint condition are calculated, and a sensitivity of the object function and a sensitivity of the constraint condition are determined (110, 112).