Abstract: A pneumatic tire the aspect ratio of which is not more than 50% has, for reinforcing a tread portion, a belt comprising at least two rubber coated cord layers having cords arranged obliquely at angles with respect to an equatorial plane of the tire of 26.degree. or more, and a belt reinforcing layer arranged outside the belt and comprising at least one organic fiber cord layer having cords arranged substantially parallel with respect to the equatorial plane of the tire. The tire is molded in a mold with a cross-sectional profile of a molded surface facing the tread portion having a radius smaller than that of a nominal tire cross-sectional profile by 1% or more of a section width of the tire and forming a convex curve to a cavity.

Abstract: A pneumatic tire comprising a cylindrical tread, a pair of sidewalls, bead rings, a radial carcass, rubber fillers each arranged between each turn-up portions and a main body of the carcass and extending from above the bead ring toward the tread portion such that the radially sectional shape of the rubber film becomes narrower toward the tread portion, and a pair of thick rubber reinforcement layers arranged on respective axially inner sides of the carcass in the sidewall portions.

Abstract: A pneumatic radial tire comprises a tread provided with a plurality of circumferential grooves extending in a circumferential direction of the tire, and plural rows of land portions defined between axially adjacent circumferential grooves and between each of edges of the tread and the adjacent main circumferential groove. That groove wall of at least the circumferential groove located nearest to at least one of the tread edges on a treading surface of the tread which is positioned on a side of the one of the tread edges is inclined to gradually increase a width of the groove toward the surface of the tread from a location spaced by 10-70% of a depth of the circumferential groove radially outwardly from a bottom thereof. The width of an opening of the circumferential groove to the surface of the tread is in a range of 3-18 mm.

Abstract: A high-speed running pneumatic radial tire comprises a cylindrical crown portion, a pair of sidewall portions extending inward therefrom, a radial carcass extending from one of the sidewall portions through the crown portion to the other sidewall portion, and a belt and a tread successively superimposed on the crown portion outward in the radial direction of the tire. The tread has plural rows of blocks defined by plural circumferential grooves and many lateral grooves, and the belt is comprised of at least two main crosscord belt layers and an auxiliary belt layer arranged thereon. The auxiliary belt layer is formed by spirally winding a rubberized ribbon ply of heat-shrinkable cords on the main belt layers, in which an overlapped amount of the ribbon ply is made large in a zone of the tread substantially corresponding to the block row than in a zone of the tread substantially corresponding to the circumferential groove.

Abstract: A high performance pneumatic radial tire comprises a toroidal carcass, a tread radially outside a crown portion of the carcass, a belt layer interposed between the carcass and the tread and having a same width of the tread, and an auxiliary layer arranged between the belt layer and the tread and covering the entire belt layer. organic cords are buried substantially parallel to an equatorial plane of the tire in the auxiliary layer, and land portions are defined between at least two circumferential main grooves formed in an outer surface portion of the tread and between the circumferential main grooves and axially opposite edges of the tread.

Abstract: To improve high speed durability or prevent tire ribs and/or blocks from being peeled off at high speed travel, a tread rubber member whose outer surface is formed into corrugation shape along tire axial direction, when seen in cross section, is prepared to form a green tire so that radially convex portions thereof may be located under tire circumferential grooves to be formed after vulcanization process and radially concave portions thereof may be located under tire ribs and/or blocks also to be formed after vulcanization process. Since the rubber flow rate of the tread rubber member under the circumferential grooves is relatively larger, when the green tire is vulcanized, the belt layers are conversely deformed into radially concave shape under the circumferential grooves.

Abstract: A low profile pneumatic radial tire comprises at least one carcass ply containing cords arranged substantially at 90.degree. relative to a circumference of a tread, and a belt consisting of at least two belt layers which are composed of metal cords inclined relative to the circumference of the tread and intersected with one another between the adjacent belt layers and which are arranged upon a crown of the carcass. The tread surrounds the crown, and is provided with a pair of circumferential main grooves which are disposed symmetrically with respect to an equatorial plane of the tire and which divide a treading portion of the tread into a central region and axially opposite side regions and which are separated by a distance ranging from 45 to 65% of a maximum width of the tire in the state that the tire is assembled onto a normal rim and inflated at a normal internal pressure.

Abstract: To improve high-speed durability of a low-section pneumatic radial tire without producing tire separation at both belt ends and expansion at both tread sidewalls after the tire has been worn off to some extent, the tire belt structure disposed between the tire tread and the carcass is composed of two belt layers and a plurality of auxiliary layers. The auxiliary layers comprises a first auxiliary layer extending over the belt layers and at least second and third auxiliary layers arranged on both axially outside end of the tread in such a way that an axially outer end of each of the auxiliary layers extends to near the tread sidewall and an axially inner end of each of the auxiliary layers extends to or beyond under at least an axially outermost circumferential groove formed on the tread in step fashion extending from tread center to tread end or vice versa.

Abstract: To prevent tire unbalanced abrasion, that is, tire unbalanced rigidity between the acute angle corners and the obtuse angle corners of blocks forming a tire tread pattern, without decreasing the tire drainage and increasing tire pattern noise, block side walls extending along the main circumferential grooves are sloped down to the bottom of the main grooves in such a way that an inclination angle between the tread surface normal line and the block side wall increases gradually from the obtuse angle corners of the blocks to the acute angle corners thereof. Preferably, the inclination angle is 8 degrees at the obtuse angle corner and 25 degrees at the acute angle corner on the wide main circumferential groove, and 7 degrees at the obtuse angle corner and 13 degrees at the acute angle corner on the main circumferential grooves adjacent to the wide main groove.

Abstract: To improve the durability and the riding comfortableness of a pneumatic safety tire having at least one carcass ply, at least one belt layer, and a pair of crescent-shaped cross-section reinforcing layers, each of the reinforcing layers comprises a higher elastic rubber layer with a hardness of 70 to 85 in Shore A and an elastic modulus of 25 to 60 kg/cm.sup.2 and an anticrack rubber layer with a hardness of 55 to 70 in Shore A and an elastic modulus of 10 to 30 kg/cm.sup.2. The maximum thickness of the reinforcing layer is preferably 4 to 12 mm. Load applied to the tire during run-flat travel is supported mainly by the higher elastic rubber layer, and crack generation due to tire deformation is reduced by the presence of the anticrack rubber layer.

Abstract: In a pneumatic low section tire with an aspect ratio (height/width) of 0.65 or less, when a green tire is pressurized with a bladder within a mold, tread rubber is forced to flow into recesses for forming a tread block pattern. With this rubber flow, the belt is subjected to deformation toward the same recesses, so that the belt layer deforms outward at the middle of the transversal grooves between two main circumferential grooves. This deformation causes the skid base rubber existing between the transversal groove bottom and the belt layer to be thin at the middle of the transversal grooves, thus resulting in an early trouble. To overcome this problem, the transversal grooves are formed in raised bottom or corrugation fashion along a longitudinal direction thereof, to obtain a uniformly thick skid base. Further, this raised bottom serves to increase the drainage effect during rainy weather running.