The present invention provides a pneumatic tire in which a steel cord carcass ply composed of an ultrafine wire having a filament diameter of 0.15 mm or less is used as a reinforcing material, and the carcass ply is positioned between the bead cords without turn-up of the carcass ply for turning up it through an annular bead bundle on an upper side of the carcass ply, such that side rigidity is maintained even when replacing two conventional fiber carcass plies with one steel carcass. Thereby, rather than the conventional turn-up method of turning up the carcass ply on the upper side of the annular bead bundle, the carcass ply passes through the bead bundles as shown in FIG. 3, such that a deformation energy of the bead portion is minimized and a rolling resistance is maximized. The tire of the present invention is characterized by satisfying a correlation equation between a height Bh1 of an inner bead bundle position and a height Ah of the bead portion including an apex of 1.2<Ah/Bh1<4.5.

In a pneumatic tire in which a reinforcing layer including a cord is embedded, a coating rubber covering the cord included in the reinforcing layer uses a rubber composition in which 30 parts by mass to 60 parts by mass of carbon black having a nitrogen adsorption specific surface area N.sub.2SA of 100 m.sup.2/g or more and 0 parts by mass or more and 10 parts by mass or less of aroma oil is optionally blended, per 100 parts by mass of a rubber component containing 70 mass % to 100 mass % of a natural rubber and in which a strength at break TB (unit: MPa) at 100° C. and a stress M100 (unit: MPa) at 100% elongation at 100° C. satisfy a relationship TB.sup.2/M100≥50.0.

The outer diameter of the pneumatic tire is 350 mm or more and 600 mm or less, and the tire width is 125 mm or more and 255 mm or less. An aspect ratio of the pneumatic tire is 40% or more and 75% or less, a rim diameter of a rim wheel is 10 inches or more and 22 inches or less, and a rim width of the rim wheel is 3.8 inches or more and 8 inches or less. The pneumatic tire satisfies the relationship of 0.78≤RW/SW≤0.99 and 0.56≤RD/OD≤0.75. The carcass has a plurality of carcass cords arranged at intervals, the carcass cords are formed of prescribed organic fibers, and the breaking strength of the carcass cords is ≥2.2 kN/cm.

In a pneumatic tire including a carcass layer mounted between a pair of bead portions and a belt reinforcing layer disposed on an outer circumferential side of the carcass layer, the carcass layer is formed of a carcass cord made of an organic fiber cord, an elongation at break of the carcass cord is set to 20% or more, an elongation under a load of 1.5 cN/dtex of the carcass cord in sidewall portions is set to from 5.0% to 8.0%, the belt reinforcing layer is formed of a cover cord made of an organic fiber cord, and a tensile strength of the cover cord per width of 50 mm at a 3.0% elongation is set to from 2.8 kN to 4.0 kN.

A tire for an agricultural vehicle (1), and in particular the carcass reinforcement (4) thereof, for a tire running at low pressure on loose ground, is to reduce the compaction of the ground and to increase the traction capability by reducing the structural stiffness of the tire. According to the invention, the carcass reinforcement (4) is made up of a single carcass layer (41) having a mean thickness E at most equal to 2 mm and a breaking strength Fr, expressed in daN/cm, that satisfies the relationship:

Fr>=Fs=(Cs*Pmax*10.sup.−3)*((R.sup.2−((R+Rj)/2).sup.2)/2)/Rj, with Fs: reference threshold strength (in daN/cm) Cs: safety factor at least equal to 1, Pmax: recommended maximum inflation pressure (in kPa), R=D/2: outside radius of the tire (in mm), Rj=Dj/2: nominal radius of the rim (in mm).

Disclosed is a pneumatic radial tire for a passenger car having ultra fine steel cords for a carcass ply in which adhesive force between a carcass ply layer and a side wall or a rim flange rubber adjacent to a turn up portion on an outside and a stiffness of the rim flange rubber are larger than a bending stiffness of the carcass ply layer so as to improve durability of a bead part while reducing poor air inletting generated at a carcass turn up portion.

In a pneumatic tire, at least one carcass layer mounted between a pair of bead portions is formed from a carcass cord formed of an organic fiber cord having filament bundles of organic fibers intertwined together, a fineness based on corrected mass of the carcass cord is from 4000 dtex to 8000 dtex, an intermediate elongation of the carcass cord at a sidewall portion under 1.0 cN/dtex load is from 3.3% to 4.2%, and a ratio G/R of an interlayer rubber gauge G between a body portion and a folded back portion to a cord diameter R of the carcass cord, at a contact region where the body portion and the folded back portion are in contact in the carcass layer, is from 0.50 to 0.60.

A pneumatic tire includes: paired bead portions respectively including annular bead cores and bead fillers disposed on an outer side in a tire radial direction of the bead cores; sidewall portions respectively extending outward in the tire radial direction from the bead portions; a tread portion connected to cuter ends in the tire radial direction of the sidewall portions to form a tread; and a carcass layer suspended between the bead portions. The carcass layer has a first ply that continuously extends between the bead portions and that has opposite end portions respectively and a second ply that continuously extends on the outer side in the tire radial direction of the first ply, wherein the first ply has higher tensile strength than that of the second ply, and the end portion is positioned on the outer side in the tire radial direction of the end.

A pneumatic tire 1 has a carcass 6 extending between a first bead portion 4A and a second bead portion 4B through a tread portion 2 and a pair of sidewall portions 3. The carcass 6 is composed of at least two carcass plies 7 including a first carcass ply 7A and a second carcass ply 7B which have the same ply length. Each of the first carcass ply 7A and the second carcass ply 7B is arranged asymmetrically with respect to the tire equator C.

A pneumatic tire includes: paired bead portions respectively including annular bead cores and bead fillers disposed on an outer side in a tire radial direction of the bead cores; sidewall portions respectively extending outward in the tire radial direction from the bead portions; a tread portion connected to outer ends in the tire radial direction of the sidewall portions to form a tread; a carcass layer suspended between the bead portions; and a belt layer provided on an outer side in the tire radial direction of the carcass layer in the tread portion. The carcass layer has a first ply that continuously extends between the bead portions and that has opposite end portions and a second ply that extends from a position in contact with an inner peripheral face of an end portion, wherein the second ply has higher tensile strength than the tensile strength of the first ply.