A three-dimensional finite element model for the bias tire improved from a two-dimensional geometric model was established. The simulation based on the model for bias tire (700－16 14PR) was carried out by using the 3-D layer element simulating tire composite embed in ANSYS software. The distributions of principal stress, shear stress and inter-laminar shear stress under the rating air pressure was study. Their influence on early-failure of the bias tire was pointed out. The results indicate that the 3-D finite element model is correct, the application of the finite element to inter-laminar shear stress is effective and has a significance for structural design of tire.