Composite ply structure for tires and method of manufacture

The method of preforming a composite ply (40) and forming a tire with said composite ply, the composite ply (40) having a primary ply (40A) and a pair of ply extensions (40B) for use in the carcass of the tire (10), the method comprising the steps of:

• cutting to a predetermined width (WA) primary ply (40A) reinforced with parallel substantially inextensible cords (41) encapsulated in unvulcanized rubber (44), the width (WA) extending between a first end (75) and a second end (76);
• applying a pair of ply extensions (40B) of predetermined widths (WB), one ply extension (40B) being overlappingly joined to a first end (75) and one ply extension (40B) being overlappingly joined to a second end (76), each ply extension (40B) being reinforced with substantially extensible parallel cords (43) encapsulated in unvulcanized rubber (44);
• precuring the overlappingly joined ply extensions (40B) to the primary ply (40A) locally along the adjoining overlapping joint surfaces (70) thereby forming a composite ply (40) having a predetermined total width (WT), the composite ply being unvulcanized except at the overlapping joints (70);
• assembling the preformed composite ply (40) into a tire;
• curing the tire wherein the tension in the cords (41) is transferred to the ply extension (40B) equally on each side of the tire (10), all stretching occurring in the ply extension cords (43) substantially equally.