Results of accelerated pavement tests (APT) at elevated temperatures on dense graded asphalt concrete and gap-graded asphalt rubber hot mix (ARHM-GG) are presented. APT testing was performed by use of a Caltrans heavy vehicle simulator. The overlays were placed on previously untrafficked sections of an existing flexible pavement. Variables included in the experiment were overlay type, ARHM-GG overlay thickness, tire/wheel type (dual/bias-ply; dual/radial, wide-base single, aircraft), and pavement temperature (40°C, 50°C, at 50 mm depth). Results presented include the rut development for the different variables, changes in layer thickness, and changes in air-void content. Analyses were performed for evaluating the relative contributions of shear deformation and densification to rut development.