A heavy-duty vehicle tire comprising a tread consisting of a crosslinked rubber composition comprising a reinforcing filler of siliceous type and a synthetic polyisoprene modified by grafting with a compound comprising at least one group Q, and at least one group A, which are joined to one another by at least one and preferably one “spacer” group Sp, in which: Q comprises a dipole containing at least one and preferably one nitrogen atom, A comprises an associative group comprising at least one nitrogen atom, Sp is an atom or group of atoms forming a bond between Q and A. The heavy-duty vehicle tire according to the invention has a satisfactorily improved rolling resistance/wear resistance compromise.