Process and apparatus for building tyres for vehicle wheels and tyre for vehicle wheels

A process for building tyres for vehicle wheels, comprising:

• forming a substantially cylindrical carcass sleeve, comprising at least one carcass ply;
• wherein
• said at least one carcass ply is formed by:
• laying consecutively adjacent strip elements one after the other around the circumferential extension of a substantially cylindrical deposition surface, the deposition surface comprising an intermediate portion axially interposed between two terminal portions, the two terminal portions having respective frustroconical zones that are tapered from respective axially outer edges defining a maximum diameter of the deposition surface, towards respective axially inner edges directed towards the intermediate portion defining an application diameter of the deposition surface, the two terminal portions defining along their entire extension a diameter of the deposition surface that is greater than the application diameter,
• the strip elements are laid one after the other to form overlap zones along respective longitudinal edges superimposed on each other,
• each overlap zone has, along a longitudinal extension thereof:
• terminal sections formed over respective terminal portions of the deposition surface, and
• an intermediate section formed over the intermediate portion of the deposition surface,
• wherein the terminal sections of each overlap zone are laterally opposite with respect to the intermediate section of said overlap zone,
• the intermediate section of each overlap zone extends from one to the other of said terminal sections along the intermediate portion of the deposition surface, and across an axial symmetry plane of the carcass sleeve, and
• the width of each overlap zone varies along the longitudinal extension of the strip elements in accordance with the variations in diameter and circumferential extension present along the deposition surface so that the intermediate section of each overlap zone, has, along its entire extension that is formed over the intermediate portion of the deposition surface, a greater overlap width than an overlap width of the terminal sections of each overlap zone formed over the respective terminal portions of the deposition surface.