The main objective of this thesis is to develop a linear flexible wheel model that, implemented in a multibody model of the ExoMars rover, allows to simulate and predict the real behavior of the rover on the Martian surface. ExoMars is the mission managed by the European Space Agency (ESA) and the Russian Federal Space Agency (Roscosmos), with the aim to deliver a surface platform and a rover on Mars, in search of a sign of life. The Martian soil is not regular, but rocky and mostly covered with loose soil. Therefore, the study of the rover mobility becomes a crucial aspect for the mission success.