The optimized design or selection of tire steering equipment is directly related to the amount of torque required for steering. Therefore, determination of steering torque is necessary for each traortation vehicle. The purpose of this project is to determine the amount of torque required for steering of dual-tires bogie in a heavy duty vehicle i.e. mobile boat hoist (MBH). The MBH studied in this project has a nominal weight traorting capacity of 300 tons distributed on 8 tires, so there are tens of tons load on each tire. In this project the analytical model of calculating steering torque for any contact area shape and contact pressure distribution is presented first. This model is based on the integration of torque of frictional forces of contact area (footprint) elements. Then a numerical (Finite Elements) model of the MBH tire is made in the ABAQUS software and the steering torque has been obtained from the finite elements (FE) model for two different states: “steering of single-tire around the center of footprint” and “steering of dual-tires bogie around the center of bogie”. In the FE model three different materials are assumed for modelling the behavior of different parts of tire (two different orthotropic and a hyperelastic material). The required coefficients for determining these materials have been estimated and then regulated and verified according to practical tests on the vehicle. The analytical and also the FE results are compared with each other and discussed. By making the rolling simultaneous with steering in dual-tires possible, since the center of rotation of each tire is transmitted from the point between two tires to the center of its footprint, the steering torque decreases greatly and will be a few more than twice amount of steering torque of single-tire. The remained difference is for the reason of existence of rolling resistance forces. Determining shape of the contact area as rectangle with elliptical ends is one of the achievements of this project. As the load on the tire increases, the length of rectangular part increases. At the end, the amount of torques obtained from the modelling are verified by doing tests of torque measurement on the MBH. Keywords: Steering, Tire, Steering torque, Footprint, Steering of dual tires vehicles, Mobile boat hoist, Finite element simulation
