| 摘要 |
Provided is a pneumatic tire which is lighter in weight and exhibits increased flat-spot resistance while keeping its durability and driving stability. The pneumatic tire according to the present invention includes a carcass layer being laid between paired right and left bead sections, and at least two belt layers being arranged at an outer peripheral side of the carcass layer in a tread section. The pneumatic tire is characterized in that a hybrid cord, used as reinforcement cords of the carcass layer, is obtained by imparting second twists, in a reverse direction of the first twists, to a bundle of: at least one rayon first twist yarn being obtained by imparting first twists to a bundle of rayon fibers; and at least one aramid first twist yarn being obtained by imparting, to a bundle of aramid fibers, first twists in the same direction of the first twists of the rayon first twist yarn. The total fineness of the hybrid cord is in a range of 3500 dtex to 9000 dtex, the second twist coefficient K of the hybrid cord expressed by Equation 1 is in a range of 1700 to 2400, the tensile strength of the hybrid cord is not less than 5.5 CN/dtex when absolutely dry, and the elongation percentage of the hybrid cord under a load of 1.8 cN/dtex is 2% to 4% when absolutely dry, <?in-line-formulae description="In-line Formulae" end="lead"?>K=T√(Tr/rhor+Ta/pa) (Equation 1)<?in-line-formulae description="In-line Formulae" end="tail"?> where T denotes the number of second twists of the hybrid cord (times/10 cm), Tr denotes the total fineness of the rayon fibers (unit: dtex), rhor denotes the specific gravity of the rayon fibers, Ta denotes the total fineness of the aramid fibers (unit: dtex), and rhoa denotes the specific gravity of the aramid fibers.
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