This paper demonstrates the applicability of the integrated Weibull approach to simulate the in situ rutting performance of asphalt concrete mixes by applying appropriate correction factors to laboratory models. The goal was to verify and calibrate the laboratory models according to accelerated pavement test results. The results of the repeated simple shear test at constant height (RSST-CH) were used to estimate the permanent deformation accumulation mechanisms. General regression equations were shown to successfully represent the Stage I and Stage II permanent deformation accumulation phases for mixes containing different binder types according to the results of RSST-CH. Correction factors were used to calibrate the laboratory equations according to the deflection data from four heavy vehicle simulator test sections to estimate in situ rutting performance. The results indicate that phase separation occurs at higher repetition values with increasing shear stress. Moreover, only Stage I of the laboratory models was actually valid at the high shear stress levels used for in situ rutting performance prediction. The simulations further confirm that the integrated Weibull approach is a successful and reliable method for prediction of the in situ rutting performance of flexible pavements and provides high coefficient of determination values.