A heavy duty tire, comprising a sidewall comprising a sidewall rubber composition, the sidewall rubber composition comprising at least one isoprene-based rubber, at least one polybutadiene rubber, and at least one oxidized carbon black having an average particle size of 30 nm or less, the sidewall rubber composition comprising, based on 100% by mass of the rubber components therein, at least 5% by mass but less than 50% by mass of the at least one polybutadiene rubber, the heavy duty tire satisfying the following relationships and: Amount of isoprene-based rubber > Amount of polybutadiene rubber wherein the amount of isoprene-based rubber and the amount of polybutadiene rubber represent the amounts, expressed in % by mass, of the at least one isoprene-based rubber and the at least one polybutadiene rubber, respectively, based on 100% by mass of the rubber components in the sidewall rubber composition; Thickness at widest point > -0.14 × Amount of polybutadiene rubber + 10.0 wherein the thickness at widest point represents the thickness (mm) of the sidewall at the widest point, and the amount of polybutadiene rubber represents the amount, expressed in % by mass, of the at least one polybutadiene rubber based on 100% by mass of the rubber components in the sidewall rubber composition, and wherein the average particle size refers to a number average particle size as determined using a transmission electron microscope. the sidewall rubber composition comprising at least one isoprene-based rubber, at least one polybutadiene rubber, and at least one oxidized carbon black having an average particle size of 30 nm or less, the sidewall rubber composition comprising, based on 100% by mass of the rubber components therein, at least 5% by mass but less than 50% by mass of the at least one polybutadiene rubber, the heavy duty tire satisfying the following relationships and: Amount of isoprene-based rubber > Amount of polybutadiene rubber wherein the amount of isoprene-based rubber and the amount of polybutadiene rubber represent the amounts, expressed in % by mass, of the at least one isoprene-based rubber and the at least one polybutadiene rubber, respectively, based on 100% by mass of the rubber components in the sidewall rubber composition; Thickness at widest point > -0.14 × Amount of polybutadiene rubber + 10.0 Amount of isoprene-based rubber > Amount of polybutadiene rubber wherein the amount of isoprene-based rubber and the amount of polybutadiene rubber represent the amounts, expressed in % by mass, of the at least one isoprene-based rubber and the at least one polybutadiene rubber, respectively, based on 100% by mass of the rubber components in the sidewall rubber composition; Thickness at widest point > -0.14 × Amount of polybutadiene rubber + 10.0 wherein the thickness at widest point represents the thickness (mm) of the sidewall at the widest point, and the amount of polybutadiene rubber represents the amount, expressed in % by mass, of the at least one polybutadiene rubber based on 100% by mass of the rubber components in the sidewall rubber composition, and wherein the average particle size refers to a number average particle size as determined using a transmission electron microscope.