We have measured and analyzed the rheological properties of a polystyrene sample of narrow molecular weight distribution in terms of the Doi‐Edwards theory from the linear to the nonlinear regimes in a consistent manner. First, the linear viscoelastic data of the polymer is correlated with the molecular weight distribution obtained by GPC. Then, a four‐component molecular weight distribution extracted from the linear viscoelasticity is used to calculate the steady‐state viscosities for comparison with experimental values. Independently we compare the experimental and theoretical values of the damping function. The good agreements between theory and experiment in both cases confirm each other, since they are directly related. The present study has also shed light on the role which the tension relaxation of the deformed chain plays at high strain rates. At deformation rates slower than the chain tension relaxation, the rheological properties are determined by the reptational process making it unnecessary to include the tension coefficient of the Curtis‐Bird theory into the calculations.