Abstract: Methodology for characterizing non-uniformity forces at a tire spindle, such as low and high speed radial force variations and high speed tangential force variations include the steps of measuring radial run out and radial or tangential force variations at high and/or low speeds. From such measurements, the contribution of a predetermined type of stiffness variation (e.g. radial, tangential, extensional, bending) to respective radial and/or tangential force variations can be determined. Signature analysis statistical methods may also be utilized to characterize such tire non-uniform forces for different steps and reference physical angles of a tire construction process. Based on the characterization of such tire non-uniform forces, additional process steps may further correspond to tire grading and/or sorting processes, physical tire modification processes and tire manufacturing processes.