Plasticizing system and rubber composition for tire containing said system

A process for preparing a rubber composition comprising at least one diene elastomer, one reinforcing filler and one plasticizing system, the process comprising the following stages:

• incorporating in the at least one diene elastomer, in a mixer:
• the reinforcing filler;
• the plasticizing system;
• kneading everything thermomechanically, in one or more goes, until a maximum temperature of between 110° C. and 190° C. is reached;
• cooling the combined mixture to a temperature of less than 100° C.;
• subsequently incorporating:
• a crosslinking system;
• kneading everything up to a maximum temperature of less than 110° C.;
• and
• extruding or calendering the rubber composition thus obtained;
• and wherein the plasticizing system comprises at least:
• one plasticizing hydrocarbon resin, the glass transition temperature (Tg) of which is greater than 0° C.;
• and
• a tri- or pyromellitate ester corresponding to the formula (I):
• wherein the R radicals, which are identical or different, represent a hydrocarbon radical and the R′ radical represents hydrogen or COOR group.