A pneumatic tire comprises a pair of bead portions each having a bottom face and an axially outer side face which contact with a bead seat and a flange of a wheel rim, respectively, wherein the axially outer side face comprises a radially outer part for contacting with a radially outermost curved portion of the rim flange; and a radially inner part for contacting with a radially inner flat portion of the rim flange. In a meridian section of the tire, the radially inner part is a substantially straight line, and the radially outer part is (A) a substantially straight line or (B) convex line or (C) a curved concave line having a radius of curvature of not less than 300 mm, and the radially outer part extends radially outwards from the radially outer end of the radially inner part while inclining axially outwards.