Bead core for agricultural tire

A bead core for a tire which is substantially rotationally symmetrical about an axis, the bead core comprising a plurality of windings of at least one metallic wire with diameter d arranged next to one another in a direction P forming an angle α with an axial direction in a radial sectional half-plane R, on N layers superposed on one another in a radial direction,

• wherein α ranges from 0° to 10°,
• wherein, in the sectional half-plane R, the windings of the bead core form a structure consisting of a base structure and a cap structure, where a radially inner base structure is directly in contact in the radial direction with a radially outer cap structure,
• wherein the base structure of I layers Ci superposed on one another in the radial direction, wherein I is odd and I≥3, comprises:
• the radially innermost layer C1 and the radially outermost layer CI comprising L windings,
• wherein i is an integral number ranging from 1 to I−2, Li=Li+2 and |Li−Li+1|=1, wherein Li is the number of windings of the layer Ci and Max(Li)=L with:
• when i is odd, each axially outermost winding of the layers Ci is arranged in contact with a first outer side, which is a straight line parallel to the radial direction and tangent to the axially outermost winding of the layer C1 in the radial sectional half-plane R, and
• when i is even, the axially outermost winding of the layers Ci is arranged in contact with the two axially outermost windings of the immediately lower layer,
• wherein the cap structure of J layers Cj superposed on one another in the radial direction comprises:
• the layer CI+1 of L−1 windings superposed on layer CI of the base structure in the radial direction and the axially outermost winding being in contact with the two axially outermost windings of the immediately lower layer, and
• or when j is an integral number between 1 and J, the layer CI+j is such that:
• when j is even, LI+j=LI+(j−1),
• when j is odd, LI+j=L−(j+1)/2,
• such that when j is odd, the layer CI+j is formed from LI+j windings and the axially outermost winding is arranged in contact with the two axially outermost windings of the immediately lower layer, and
• when j is even, the layer CI+j comprises LI+j windings arranged next to one another in the direction P from the first outer side,
• or when j ranges from 1 to J, the layer CI+j is such that:
• LI+j=L−j,
• wherein a product of the diameter d times L ranges from 13.0 mm to 25.0 mm,
• wherein N, I and J are integral numbers not equal to zero, such that N=I+J is less than or equal to 16, and
• wherein a radially outermost layer of the cap structure has less windings than any layer in the base structure.