The disposal of waste tyres has emerged as a significant environmental challenge due to their non-biodegradable nature, large volume generation, and associated fire and health hazards. In the context of sustainable infrastructure development, the utilization of waste tyre rubber in pavement base and sub-base layers presents a promising alternative for both waste management and performance enhancement of flexible pavements. This study investigates the feasibility, engineering behavior, and structural performance of pavement base and sub-base materials modified with waste tyre rubber in various forms such as shredded rubber, crumb rubber, and rubber chips. Laboratory experimental investigations were conducted to evaluate key geotechnical and mechanical properties including compaction characteristics, California Bearing Ratio (CBR), unconfined compressive strength (UCS), resilient modulus, permeability, and durability. The influence of rubber content on density, stiffness, deformation characteristics, and energy absorption capacity was systematically analyzed. Results indicate that controlled incorporation of waste tyre rubber improves ductility, fatigue resistance, and resistance to cracking while contributing to reduction in material brittleness. However, excessive rubber content leads to reduction in load-bearing capacity due to lower stiffness and density. The study identifies optimum rubber content ranges suitable for base and sub-base applications based on performance criteria. Environmental and economic benefits, including reduced landfill burden, conservation of natural aggregates, and lifecycle cost savings, are also discussed. The findings support the potential of waste tyre rubber as a sustainable geomaterial for pavement applications, contributing to circular economy principles and resilient road infrastructure.