This paper introduces methods for determining characteristics grip pull tractor wheels based on rheological models of the earth. Basis of this method is based on the nature of the relationship between strain and deformation of soil is nonlinear, the earth is affected when the wheel is first compressed, Reo flow and elasticity characterized by the parameters Ct hard damping coefficient needs to run n, up , uv and compression resistance. The model describes both viscous and elastic properties as soil depth z is called soil rheology model. With cycloid shear test can determine the coefficient of rheological models, which can be determined according to the angle of the cutting force and the radial pressure on the area of the plate and cut. Finally define specific parameters for features like drag wheels sticking tangential traction, sticking coefficient, drag coefficient and the coefficient of rolling resistance.