Tube bends are critical in an exhaust system. The acceptability of tube bends is based on the induced level of shape imperfections considered. An analysis is presented for the performance tuning of the genetic algorithm including the importance of raw material selection, ovality and elongation property. This study is an attempt to analyze the ovality effect of STAC 60/60 material. CAE tools are essential to exploit the design of experiments and find out the optimum values of the design parameters in comparison with full factorial designs.Especially the effects of materials, dimensions and geometry shape of the ultimate strength were discussed by both CAE and experiments. The ultimate strength of steel tube was evaluated at least 20-30% as a local strain independent of the materials. The dependency of ultimate bending angle on original centre angle of the tube bend was clarified.The finite element method is used to model and analyze a stand-alone, long-radius tube bend with 50.8 mm nominal diameter and a 100 mm bend radius with specified length. The computed results are compared and the effects of total deflection and stresses of the tube bends are noted. The final objective of this paper is to optimize the allowable design strain or deformation of particular steel tube bend from the standard design tolerances.