| 摘要 |
A pneumatic tire includes a low conductive rubber portion forming at least a cap rubber portion of the tread rubber which provides a tread surface of the tire. A narrow high conductive rubber strip extends in a radial direction of the tire at a widthwise center region of the cap rubber portion, and is exposed to the tread surface to form a discharge path for allowing electrostatic charges of a vehicle body to be discharged to a road surface. An unvulcanized tread rubber for the tire is obtained by passing a high conductive unvulcanized rubber through a passage extending from an extruder unit to the back side of an extrusion orifice, to form at least part of the remaining potion of the tread rubber. The high conductive unvulcanized rubber while passing through the passage is partly introduced into a narrow branch passage and passed through a slit-like opening having a cross-sectional shape which is substantially straight in a height direction of the extrusion head and situated in the vicinity of the back side of the extrusion orifice, to form the narrow strip of the high conductive rubber in a composite body of different kinds of unvulcanized rubbers.
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