Rubber composites filled with carbon black and mica flakes were investigated by solid-state NMR and dynamic mechanical measurements. The results show that in rubber (butyl, EPDM, and chloroprene) and rubber composites filled with mica flakes there exists an interphase of considerable fraction with a different T1ρ value from the matrix. The hindered segmental motion in this interphase appears in the dynamic mechanical measurement with a high and broad tan δ and a high loss modulus E". The value of E" increases with increasing percentage of mica.