The friction of elastomers has at the present time a huge role in the functionality of final products, especially on tires. In this paper it is shown how the frictional properties of rubber materials are changing under the action of temperature and pressure. For this, speed-dependent experiments are performed to determine the coefficient of friction of a tire tread compound on rough self-affine surfaces, such as granite. Therefore both the temperature – to verify the time-temperature-superposition, as well as the load was varied. Further simulations with the theory of Klüppel and Heinrich were carried out in order to make a prediction of the coefficient of friction varying the pressure and compared to the experimental data. It was found that a good description of the experimental data by the present theoretical model is possible. In addition a closer look at the physical mechanisms that occur during friction process is given.