Rubber is one of the most important materials of modern industry and have a wide range of usage owing to a number of superior properties. In this study, the mechanical behaviour of the metal-rubber combination pulley part transferring motion in the engine through the timing belt was examined by the finite element method, confirmed experimentally, and optimized. Uniaxial tension and pure shear tests were carried out physically to develop a hyperelastic material model. 3 parameter Mooney-Rivlin hyperelastic material constants were calculated by using force-elongation values obtained from uniaxial tension and, pure shear tests. Afterwards, pulley geometry was modelled, and displacements, stresses, reaction moments were examined under various torsional loadings. To confirm the accuracy of the pulley analysis, a servomotor driven pulley torsion testing machine was designed and manufactured. Then, torque and angle values were measured by testing the pulley parts at the same torsional angles. By this study, it was proven that mechanical behaviour of pulley can be expressed numerically. After validation of the material model and the results obtained using analysis method, the pulley geometry was further improved the stress levels on the rubber material were reduced 28% under the same loading conditions by using optimization tools.