Thermoplastic elastomers (TPE) and ethylene-propylene-diene monomers (EPDM) may be used in place of thermoplastic rubbers in extrusion and injection processes because they are eco-friendly and recyclable. One of the best examples of such usage is in automotive weatherstripping. The nonlinear properties of the TPE and EPDM components are important parameters for evaluating the behavior of weatherstripping. Uniaxial and equi-biaxial tension tests were performed to obtain material constants and stress-strain curves. The TPE and EPDM components used in weatherstripping were then analyzed with a commercial nonlinear finite element software package. The results demonstrated that this method can be used to predict the behavior of TPE and EPDM components in weatherstripping.