The invention relates to a tire rubber composition based on at least one diene elastomer, an inorganic filler as reinforcing filler, a coupling agent providing the bonding between the inorganic filler and the diene elastomer, characterized in that the coupling agent is an azosilane compound of following formula (I): (G1)3-a(G2)aSi—Z—NH—C(O)—N═N—C(O)—NH—Z—Si(G1)3-a(G2)a  (I) in which: G1, identical to or different from one another, each represent a monovalent hydrocarbon-based group chosen from branched or unbranched, substituted or unsubstituted alkyls, having from 1 to 18 carbon atoms, substituted or unsubstituted cycloalkyls or aryls, having from 5 to 18 carbon atoms, G2, identical to or different from one another, each represent a hydroxyl group or a monovalent group in the form (G3)n-OG1 in which G3 is a divalent linking group having from 1 to 18 carbon atoms and comprising one or more heteroatoms chosen from O, S, Si and N, n being a number equal to or higher than 0 and less than or equal to 18, Z represents a divalent linking group having from 1 to 18 carbon atoms, a is equal to 1, 2 or 3.