Flow number (FN) reflects the resistance of asphalt mixtures against rutting failure by assessing the results of repeated loading permit deformation (RLPD) testing, affecting the different loading regimes. Accordingly, this work was conducted to investigate the impact of loading variables, i.e., loading duration, rest ratio, and loading pulse waveform, in addition to the testing temperature on the permanent deformation accumulation. Square and Haversine waveforms were chosen as the loading waves. Besides, three levels of loading duration (100, 500, and 1000 ms), two levels of rest ratios (1 and 3), and two testing temperatures (40 and 55 °C) were considered in the definition of loading regimes. The Francken model was fitted over the experimental data aim to determine the FN points. Weibull distribution analysis was also applied to distinguish between the different levels of testing variables. The results indicated that testing temperature was the most significant variable in permanent deformation accumulation, and loading duration was the most effective in defining loading regimes. Increasing loading duration and rest ratios resulted in an increased rate of permanent deformation accumulation and lower FN values. The specimens exposed to the square waveform were reached the FN sooner than those exposed to haversine.