Pneumatic tire having tread including pair of axially outer base rubber layers

A pneumatic tire comprising

• a carcass extending between bead portions through a tread portion and sidewall portions;
• the thread portion including a grooved portion;
• a belt disposed radially outside the carcass in the tread portion, and
• a tread rubber disposed radially outside the belt, said tread rubber comprising a radially outer tread rubber layer,
• an axially inner base rubber layer having a substantially constant thickness, and
• a pair of axially outer base rubber layers, wherein at a boundary between the axially inner base rubber layer and each said axially outer base rubber layer, the thickness of the axially inner base rubber is the same as the thickness of the axially outer base rubber layer, with the ratio of the thickness of the radially outer tread rubber layer to the thickness of each of the axially inner and outer base rubber layers being greater than 2.0, with the exception of the grooved portion;
• and
• said axially inner base rubber layer disposed on the radially outside of the belt and centered in the tread width, said axially outer base rubber layers disposed one on each side of the axially inner base rubber layer, on the radially outside of the belt, said radially outer tread rubber layer disposed over the radially outside of the axially inner and outer base rubber layers,
• the radially outer tread rubber layer having a hardness HC in a range of from 60 to 80 degrees, the axially inner base rubber layer having a hardness HB1 in a range of from 50 to 65 degrees,
• the axially outer base rubber layers having a hardness HB2 in a range of from 75 to 95 degrees, and
• the hardness HC, hardness HB1 and hardness HB2 satisfying the condition HB1<HC<HB2.