Vessel-centering determination carried out as a part of Enhanced Mechanical Calibration is the most sensitive parameter to vessel inconsistencies and therefore tightly controlled. The FDA/ASTM criterion for vessel centering is 1.0 mm. However, the impact of off-centered vessels on drug release and dissolution has not been evaluated. We attempted to design a practical approach to evaluate a critical tolerance range around the acceptance criteria. Experiments were conducted by manually adjusting vessels to varying degrees of off-center. Dissolution testing was carried out using USP Prednisone Tablets RS, and the geometric mean and %CV were calculated using the PVT calculation tool and template and assigned pass/fail criteria based on the USP acceptance criteria. The test results passed Stage 1 at nominal and ≈1.0-mm centering conditions and passed the ≈1.5-mm condition at Stage 2. The PVT results failed at ≈2.0-mm centering condition. The data indicate that a stricter alignment practice might be necessary during calibration and routine use to ensure vessel centering is maintained per the FDA criteria. An ad hoc policy allowing no investigation for centering values greater than 1.0 mm but less than 1.5 mm during calibration might be suitable for routine maintenance of dissolution Apparatus 1 and 2.