This paper shows that the stiffness of styrene–butadiene solid rubber with added kaolin powder is related to the yield stress of kaolin dispersion in liquid polybutadiene rubber up to the percolation threshold. For five kinds of kaolin powder, the value of τ° spans the range of 100–430 Pa, while the corresponding compressive elastic constant of SBR varies from 12 to 21 MPa. A relationship between τ° and ΔE i /*E R is proposed. Critical examination of these data infers that kaolin powder dispersed in solid rubber matrix acts as an additive which decreases the random movement of the polybutadiene chains. Consequently, dispersions of nano-particles in liquid and in solid SBR are considered to be related, thus leading to a rheological method for selecting nano-particles as fillers in solid SBR. This paper shows that the stiffness of styrene-butadiene solid rubber with added kaolin powder is related to the yield stress of kaolin dispersion in liquid polybutadiene rubber up to the percolation threshold. For five kinds of kaolin powder, the value of τ ° spans the range of 100-430 Pa, while the corresponding compressive elastic constant of SBR varies from 12 to 21 MPa. A relationship between τ ° and ΔE i / * ER is proposed. Critical examination of these data infers that kaolin powder dispersed in solid rubber matrix acts As an additive which decreases the random movement of the polybutadiene chains. Therefore, dispersions of nano-particles in liquid and in solid SBR are considered to be related, thus leading to a rheological method for selecting nano-particles as fillers in solid SBR.