This study presents a comprehensive material characterization program to develop the database inputs required for implementing the Mechanistic–Empirical Pavement Design Guide (MEPDG) in the United Arab Emirates (UAE). Five asphalt concrete (AC) mixtures were evaluated, including two conventional penetration-grade binders (PEN 40/50 and PEN 60/70) and three SBS-modified binders (PG70E–0, PG76E–10, and PG82E–22). The experimental program followed AASHTOWare Pavement ME Design requirements and included asphalt binder testing (penetration, softening point, rotational viscosity, DSR, and BBR) and AC mixture testing (dynamic modulus, flow number, axial fatigue, and indirect tensile strength). The results showed that SBS-modified binders and mixtures, particularly PG70E–10 and PG82E–22, exhibited improved rheological behavior, reduced permanent deformation, and enhanced fatigue resistance, while PG76E–10 demonstrated intermediate performance, highlighting the influence of polymer formulation and mixture structure. Pavement ME simulations indicated that Level 1 material inputs preserved laboratory-observed performance trends, resulting in lower predicted rutting, fatigue cracking, and International Roughness Index (IRI). In contrast, Level 3 inputs masked material-specific behavior and, in some cases, altered mixture performance rankings. These findings emphasize the necessity of mixture-level testing and Level 1 inputs for reliable mechanistic–empirical pavement design under UAE climatic and traffic conditions.