Rubber mixtures containing at least one rubber, at least one filler and at least one compound of formula wherein R1, R3, R6 and R8 are identical or different and represent methyl or ethyl, R4 and R5 are identical or different and represent methyl or ethyl, R2 and R7 are identical or different and represent methyl or ethyl and x=4, and the vulcanizates obtainable therefrom and moldings containing said vulcanizates. The latter feature high strength and breaking elongation, low rolling resistance and good wet grip as well as low emission of VOC during production.