Tire manufacturing method

A tire manufacturing method for vulcanizing a green tire using a rigid inner mold comprising an outer surface for molding an inner cavity surface of a pneumatic tire, the method comprising:

• a step of forming the green tire on the outer surface of the rigid inner mold;
• and
• a vulcanization step of vulcanizing the green tire on the rigid inner mold, wherein the rigid inner mold comprises:
• an inner mold body comprising a plurality of segments forming an annular shape with a central hole upon being assembled,
• a core disposed in the central hole and substantially constraining the respective segments to hold the inner mold body in the annular shape, and
• an outer diameter adjusting means for changing an outer diameter of the core by changing a temperature of the core such that the respective segments move outward in a radial direction of the tire to increase a gap between adjacent segments by an expansion of the outer diameter of the core, and the respective segments move inward in the radial direction of the tire to increase a level difference of outer surfaces between adjacent segments by a reduction of the outer diameter of the core,
• wherein the vulcanization step comprises an adjustment step of adjusting the outer diameter of the core by the outer diameter adjusting means so that the gap and the level difference fall within predetermined ranges,
• wherein prior to the adjustment step, the tire manufacturing method further comprises a preparation step of preliminarily obtaining a relationship between the temperature of the core and the gap or level difference, and
• the adjustment step regulates the temperature of the core based on the relationship.