A structure/property relationship is developed between the dynamic storage modulus, E’, and the cross-polarization time constant T(CH) for a series of polyurethane elastomers. The correlations made are based on the standard linear solids model (SLSM) and on the concept that T(CH) is Modulated by near static molecular motions. The use of the SLSM to describe the main viscoelastic range of these polyurethanes is contrasted to previous models used to develop similar correlations.