The invention relates to a sulphur-vulcanizable rubber compound for the production of tread rubbers for tyres, which contains at least one diene rubber, at least one silane coupling agent, at least one filler interacting with the silane coupling agent and further conventional additives. For a reduced loss factor tan at 55°C, the rubber compound contains as the silane coupling agent at least one substance of the following structure: Z-R2X-R1-Sn-R1-X-R2-Z, where Z is selected from the group comprising: formula (I), wherein R3 is an alkyl group with (1 to 4) carbon atoms, a cycloalkyl group with 5 to 8 carbon atoms or a phenyl radical, where the R3 in a molecule may be the same or different, R4 is an alcoxy group with (1 to 4) carbon atoms, a cycloalkoxy group with (5 to 8) carbon atoms or a phenoxy group, where the R4 in a molecule may be the same or different, where R1 and R2 are alkylene groups that are different from one another with (1 to 18) carbon atoms, where X is selected from sulphur or oxygen, and with n = 2 to 8.