Process and apparatus for building tyres for vehicle wheels

A process for building a tyre for a vehicle wheel, comprising the steps of:

• i) providing a building drum having a first outer circumferential surface;
• ii) engaging auxiliary support members with the building drum, each auxiliary support member being in axially approached relationship with an axial end of the building drum, said auxiliary support members each having a second outer circumferential surface extending in a continuation of said first outer circumferential surface, wherein said second outer circumferential surface has a plurality of non-stick circumferential portions and a plurality of sticking circumferential portions, the non-stick portions and sticking portions being arranged in an alternating manner along the axial extension of each auxiliary support member and comprising:
• a first sticking circumferential portion having an axial width of between about 20% and about 35% of an overall axial width of one of said auxiliary support members;
• iii) applying at least one tyre component around at least said second outer circumferential surface, said tyre component lying partly on at least one of said sticking circumferential portions and partly on at least one of said non-stick circumferential portions;
• and
• iv) axially moving said auxiliary support members away from said building drum,
• wherein step iii) further comprises:
• sticking a starting end of a continuous elongated element of elastomeric material onto the first sticking circumferential portion;
• and
• laying said continuous elongated element of elastomeric material into coils disposed in a side by side relationship or in an at least partly overlapped relationship on said second outer circumferential surface.