Vehicle dynamic simulations demand tire models, which are computationally efficient and capable of reliably predicting the dynamics of the tire. Such simple steady state and transient reduced order models are also required by tire designers to make preliminary predictions concerning behavior and judge quantitatively the relative importance of each of the subcomponents. In the realm of three dimensional multi-body dynamics, most models used are semi-empirical, where the tire is characterized by a set of equations. While the highest hierarchy in the modeling regime is a full three dimensional finite element model, the ensuing deformable multi-body dynamics is not economical for simulation. In this paper we offer an exact methodology to extract tire physical properties in order to develop a reduced order model equivalent to a complete Finite Element tire. A three-dimensional flexible ring with twin radial membrane sidewall (3DTRM Tire) is developed based on these parameters and validated for lateral, longitudinal and modal dynamics against the Finite Element model. Linear sidewall is replaced with a twin radial non-linear string sidewall providing an insight into the mechanics of the sidewall. The static and dynamic stiffness are matched and the sensitivity of the 3DTRM Tire to these crucial parameters under different loading conditions and inflation pressure are studied. Belt torsion, countered by the twin radial sidewall during cornering and the perceived invariance of lateral dynamics to belt stiffness variation is highlighted.