Procedure for producing a multi-compound tread for road vehicle tires

A process for the manufacture of a tread band, wherein the blocks thereof include different portions having differing hysteresis losses. The process includes a step for the extrusion of a preliminary tread band consisting of a first rubber compound and an injection step, wherein the preliminary tread band, once extruded, is subjected to the action of at least one injector arranged such as to penetrate into the layer of the preliminary tread band and to release a second rubber compound, which is distributed within the layer consisting of the first compound, maintaining exposed a surface that is suitable for defining a portion of the ground-contacting surface of the resulting tread band.