Method of preparing curable-rubber mixtures containing silica, for producing treads

A method of preparing curable-rubber mixtures containing silica, for producing treads, the method being characterized by comprising at least a first step to obtain a first mixture by simultaneously loading into a mixer and mixing together at least a cross-linkable unsaturated-chain polymer base, a silica reinforcing filler, and a silane bonding agent;

• said first step being stopped upon said first mixture reaching a temperature ranging from 155° C. to 175° C.;
• the method further comprising a second step to obtain a second mixture by adding to, and dispersing in, the first mixture at least one non-curing ingredient, wherein the second mixture is mixed in one uninterrupted mixing comprising a first part, in which said mixer is operated at a high first mixing speed, the first part terminating on reaching a temperature ranging from 120° C. to 145° C., and a second successive part, in which the mixer is operated at a second mixing speed lower than the first mixing speed, the second part mixing speed maintaining the temperature ranging from 150° C. to 165° C.;
• and the method further comprising a third step to obtain a third mixture by adding to, and dispersing in, the second mixture at least one curing agent;
• said third step being stopped at a temperature below a curing temperature of the third mixture.