.The invention concerns a elastomer composition for use in making tyres, based on at least (i) one diene elastomer, (ii) one inorganic filler as reinforcing filler and (iii) as coupling agent (inorganic filler/diene elastomer), one organosilicon compound having at least two functions capable of being grafted on the elastomer by means of a sulphur-containing group with polybenzothiazyl function, of formula (I): ≡Si -Z-Sx-Bzt,(AA)y, wherein: Z is a linear or branched divalent binding group for binding the polybenzothiazyl group with a silicon atom of the organosilicon compound; x is a whole or fractional number from 2 to 4; Bzt represents the 2-benzothiazole group, optionally substituted; AA represents an oxygenated organic or mineral monoacid or a polyacid, whereof at least one of the acid functions exhibits constant ionization in water, pKa, at 25 °C, higher than 3; y is a whole or fractional number other than 0 and not greater than 3. The invention also concerns tyres and tyre running treads comprising such a composition.