We studied the conductive and mechanical properties of polymer composites based on styrene butadiene rubber as a matrix and three different carbon fillers, namely graphite, graphene and carbon nanotubes. Based on the analysis of the resistivity dependences on the concentrations of various fillers, the values of percolation thresholds were determined. The sensitivity of the resistivity of all synthesized composites to the degree of their uniaxial stretching was investigated. The maximum values of the gauge factor were observed in composites with graphene filler. It was also found that in composites with carbon nanotubes as a filler, the deformations arising under applied stresses have an elastic character. After removing the tensile stresses, these composites completely relaxed to their initial size. Contrary to this, in composites with graphite and graphene, even minimal stresses caused the appearance of plastic deformations, and their complete relaxation did not occur after stress was removed.