A system and related method for improving tire uniformity includes identifying at least one candidate process effect and a corresponding process harmonic number for each process effect. A given uniformity parameter, such as radial or lateral run-out, balance, mass variation, radial lateral or tangential force variation, is measured for each tire in a test set, such that the measurements contain tire harmonics as well as a process harmonics corresponding to each candidate process effect. Rectangular coordinate coefficients are electronically constructed for each said process harmonic, after which point the rectangular coordinates corresponding to each process harmonic are solved for (e.g., by using regression-based analysis). The magnitude of each said process harmonic is estimated, and a final magnitude estimate for each process harmonic can be determined by summarizing (e.g., by taking the average or median value) the respectively estimated magnitudes for each process harmonic across all test tires.