A heavy duty tire, comprising a tread portion, the tread portion including a shoulder region (Ye) located axially outward from an axially outermost main longitudinal groove (ge) extending in a circumferential direction, the tread portion being provided with a tread rubber consisting of a multilayer structure including a cap rubber layer forming a tread outer surface and a radially innermost base rubber layer, the cap rubber layer in the shoulder region (Ye) comprising at least one rubber component including a polybutadiene rubber and a carbon black, characterized in that the heavy duty tire is satisfying the following relationships to: Tb / Tc ≤ 0.50; Eb ′ / Ec ′ ≤ 0.60; and Bca / Tb / Tc ≥ 40 wherein Tc and Ec' denote a thickness and a complex modulus, respectively, of the cap rubber layer in the shoulder region (Ye); Tb and Eb' denote a thickness and a complex modulus, respectively, of the base rubber layer in the shoulder region (Ye); and Bca denotes a polybutadiene rubber content based on 100% by mass of a rubber component content in the cap rubber layer, wherein Ec' and Eb' are the complex moduli measured under conditions including a temperature of 70°C, an initial strain of 10%, a dynamic strain of ±2%, a frequency of 10 Hz, and an extension mode, and further Ec' and Eb' refer to the complex moduli of test samples having a size of 4 mm in width, 40 mm in length, and 2 mm in thickness cut out of the cap rubber layer and the base rubber layer, respectively, of the tire as measured at a temperature of 70°C, an initial strain of 10%, a dynamic strain of ±2%, and a frequency of 10 Hz using a viscoelastic tester, and in the measurement, the longitudinal direction of the samples is adjusted to correspond to the circumferential direction of the tire, and the dynamic strain is applied to the samples in their longitudinal direction. the tread portion including a shoulder region (Ye) located axially outward from an axially outermost main longitudinal groove (ge) extending in a circumferential direction, the tread portion being provided with a tread rubber consisting of a multilayer structure including a cap rubber layer forming a tread outer surface and a radially innermost base rubber layer, the cap rubber layer in the shoulder region (Ye) comprising at least one rubber component including a polybutadiene rubber and a carbon black, characterized in that the heavy duty tire is satisfying the following relationships to: Tb / Tc ≤ 0.50; Eb ′ / Ec ′ ≤ 0.60; and Bca / Tb / Tc ≥ 40 wherein Tc and Ec' denote a thickness and a complex modulus, respectively, of the cap rubber layer in the shoulder region (Ye); Tb and Eb' denote a thickness and a complex modulus, respectively, of the base rubber layer in the shoulder region (Ye); and Bca denotes a polybutadiene rubber content based on 100% by mass of a rubber component content in the cap rubber layer, wherein Ec' and Eb' are the complex moduli measured under conditions including a temperature of 70°C, an initial strain of 10%, a dynamic strain of ±2%, a frequency of 10 Hz, and an extension mode, and further Ec' and Eb' refer to the complex moduli of test samples having a size of 4 mm in width, 40 mm in length, and 2 mm in thickness cut out of the cap rubber layer and the base rubber layer, respectively, of the tire as measured at a temperature of 70°C, an initial strain of 10%, a dynamic strain of ±2%, and a frequency of 10 Hz using a viscoelastic tester, and in the measurement, the longitudinal direction of the samples is adjusted to correspond to the circumferential direction of the tire, and the dynamic strain is applied to the samples in their longitudinal direction. the heavy duty tire is satisfying the following relationships to: Tb / Tc ≤ 0.50; Eb ′ / Ec ′ ≤ 0.60; and Bca / Tb / Tc ≥ 40 wherein Tc and Ec' denote a thickness and a complex modulus, respectively, of the cap rubber layer in the shoulder region (Ye); Tb and Eb' denote a thickness and a complex modulus, respectively, of the base rubber layer in the shoulder region (Ye); and Bca denotes a polybutadiene rubber content based on 100% by mass of a rubber component content in the cap rubber layer, wherein Ec' and Eb' are the complex moduli measured under conditions including a temperature of 70°C, an initial strain of 10%, a dynamic strain of ±2%, a frequency of 10 Hz, and an extension mode, and further Ec' and Eb' refer to the complex moduli of test samples having a size of 4 mm in width, 40 mm in length, and 2 mm in thickness cut out of the cap rubber layer and the base rubber layer, respectively, of the tire as measured at a temperature of 70°C, an initial strain of 10%, a dynamic strain of ±2%, and a frequency of 10 Hz using a viscoelastic tester, and in the measurement, the longitudinal direction of the samples is adjusted to correspond to the circumferential direction of the tire, and the dynamic strain is applied to the samples in their longitudinal direction.