The dataset contains raw mechanical data from laboratory fault reactivation experiments on pre-stressed granite/granitoid samples, along with experimental parameters and MATLAB processing code for data deduction. The raw time-series data were recorded using a triaxial-shear apparatus with ISCO pumps and an LVDT sensor, and include pressure, pump volume, flow rate, timestamp, and axial displacement measurements. A README is included with column descriptions, units, notes on dry experimental conditions, and processing guidance. This dataset supports a study that presents a unified model for forecasting the maximum magnitude of earthquakes triggered by fluid injection. The model incorporates fault pre-stress and distinguishes between two rupture regimes: contained ruptures, where slip is limited to the pressurized zone, and uncontained ruptures, where rupture extends beyond the pressurized reservoir but self-arrests before becoming runaway. We derive a simple linear scaling between seismic moment and injected volume that holds for both regimes. However, the dependence on fault pre-stress (S) shows opposite behavior: normalized moment decreases with increasing pre-stress for uncontained ruptures, while it increases for contained ruptures. As a result, higher pre-stress unexpectedly reduces the size and energetics of uncontained ruptures compared to contained ones. The predictions are validated through laboratory experiments on pre-stressed faults using discrete pressurized patches, dynamic rupture simulations, and field observations. The model successfully reproduces scaling relations across ~18 orders of magnitude in seismic moment and ~6 orders in length scale.