A tire whose pressure-proofing performance and impact durability can be improved, is provided. The tire includes: a tire frame member which is made of resin and includes: a bead portion covering a bead core; a side portion extending outwardly in a tire radial direction from the bead portion; and a crown portion extending inwardly in a tire width direction from the side portion, and the tire also includes a reinforcing layer which includes plural cords covered by resin or rubber and which extends from the bead portion to the side portion of the tire frame member to cover at least an inner peripheral surface of the side portion.

Disclosed is a tire-reinforcing steel cord for a radial tire. The tire-reinforcing steel cord has a double layer structure including a first-layer core and a second-layer core provided on the surface of the first-layer core. The first-layer core has an elliptical or rectangular cross section. The tire-reinforcing steel cord can improve processability, fatigue characteristics, and rolling resistance performance of a tire, resulting in improved fuel efficiency. A radial tire using the tire-reinforcing steel cord is also disclosed.

A steel cord for rubber reinforcement that has a construction with an outer layer and an inner strand surrounded by and adjacent to the outer layer, the inner strand having at least one steel filament with a number of N.sub.1 and an average diameter of d.sub.1 expressed in mm, the outer layer having steel filaments with a number of N.sub.2 and an average diameter of d.sub.2 expressed in mm. The inner strand has a torque T.sub.1 and the outer layer has a torque T.sub.2, the relation between T.sub.1 and T.sub.2 is defined. By doing this, the tip rise problem of the rubber ply reinforced by steel cords is reduced.