The present invention provides a tire with a belt having relatively high durability by improving fatigue resistance of cords at end portions of a circumferential belt layer, in particular, and especially proposes a radial tire for heavy load, having a relatively small aspect ratio. For this purpose, the present invention provides a tire having a carcass as a skeleton provided in a toroidal shape over a pair of bead portions, a belt disposed on the outer side in the radial direction of the carcass, and a tread disposed on the outer side in the radial direction of the belt, the belt including: at least one layer of circumferential belt layer disposed on the outer side in the radial direction of a crown portion of the carcass and formed of a number of cords extending along the equatorial plane of the tire and coating rubber thereon; and at least two layers of slant belt layers disposed on the circumferential belt layer and each formed of a number of cords extending in a direction inclined with respect to the equatorial plane O of the tire and coating rubber thereon, characterized in that: a width of the circumferential belt layer is no less than 60% of the total width of the tire; a width of at least one of the slant belt layers is wider than the width of the circumferential belt layer; and modulus of elasticity of first cords disposed on an end portion side in the widthwise direction of the circumferential belt layer is lower than modulus of elasticity of second cords disposed on the inner side in the widthwise direction of the first cords.