Method for manufacturing webs that are intended to be involved in the makeup of a reinforcing ply for a tyre, preferably for a pneumatic tyre, said method comprising the following steps: (i) a preparation step (a), during which a plurality of separate reels (6, 106, 206) are prepared, each containing a strip, known as a "straight-thread strip" (7, 107, 207), which is formed of a plurality of continuous reinforcing threads that are embedded in at least one layer of rubber and extend parallel to one another in the longitudinal direction (X7, X107, X207) of said strip, each of said straight-thread strips (7, 107, 207) having, perpendicularly to its reinforcing threads, a predetermined width known as the "frontal width" (W7, W107, W207); then (ii) a butt-joining step (b), during which the straight-thread strips (7, 107, 207) contained on said plurality of separate reels (6, 106, 206) are unwound simultaneously, and said straight-thread strips (7, 107, 207) are butt-joined in pairs in one and the same common longitudinal direction, so as to combine all of said straight-thread strips into a straight-thread ply, the reinforcing threads of which extend in the common longitudinal direction, and which has, perpendicularly to said reinforcing threads, a straight-thread ply frontal width that is greater than the individual frontal width (W7, W107, W207) of each straight-thread strip; then (iii) a cutting step (c), during which the straight-thread ply is inserted into a cutter that has a given maximum cutting capacity, known as the "cutter inlet width", which corresponds to the largest frontal width of a straight-thread ply that can be inserted into the inlet of said cutter, then, by means of said cutter, the straight-thread ply is severed transversely, several times over, in a cutting direction that is secant to the direction of the reinforcing threads, so as to form portions of straight-thread ply known as "webs" of predetermined length; the said method being characterized in that the frontal width of the straight-thread ply that is produced during the butt-joining step (b) and then inserted into the cutter during the cutting step (c) is equal to or greater than 50%, preferably equal to or greater than 75%, preferentially equal to or greater than 80%, or even equal to or greater than 90%, of the cutter inlet width, whereas the widest frontal width (W7, W107, W207) of the straight-thread strips that are butt-joined to make said straight-thread ply is less than or equal to 50%, preferably less than or equal to 40%, preferentially less than or equal to 25%, optionally, preferably, less than or equal to 10%, or even less than or equal to 5%, of said cutter inlet width. (i) a preparation step (a), during which a plurality of separate reels (6, 106, 206) are prepared, each containing a strip, known as a "straight-thread strip" (7, 107, 207), which is formed of a plurality of continuous reinforcing threads that are embedded in at least one layer of rubber and extend parallel to one another in the longitudinal direction (X7, X107, X207) of said strip, each of said straight-thread strips (7, 107, 207) having, perpendicularly to its reinforcing threads, a predetermined width known as the "frontal width" (W7, W107, W207); then (ii) a butt-joining step (b), during which the straight-thread strips (7, 107, 207) contained on said plurality of separate reels (6, 106, 206) are unwound simultaneously, and said straight-thread strips (7, 107, 207) are butt-joined in pairs in one and the same common longitudinal direction, so as to combine all of said straight-thread strips into a straight-thread ply, the reinforcing threads of which extend in the common longitudinal direction, and which has, perpendicularly to said reinforcing threads, a straight-thread ply frontal width that is greater than the individual frontal width (W7, W107, W207) of each straight-thread strip; then (iii) a cutting step (c), during which the straight-thread ply is inserted into a cutter that has a given maximum cutting capacity, known as the "cutter inlet width", which corresponds to the largest frontal width of a straight-thread ply that can be inserted into the inlet of said cutter, then, by means of said cutter, the straight-thread ply is severed transversely, several times over, in a cutting direction that is secant to the direction of the reinforcing threads, so as to form portions of straight-thread ply known as "webs" of predetermined length;