Granular-jamming chain-mail metamaterials (CMMs) exhibit remarkable programmable stiffness, positioning them as promising candidates for load-bearing and morphing applications. Inspired by modular interlocking block systems, this study introduces four unit types—compression-torsion, auxetic, spherical, and microcrystalline—that interlock to form a CMM system with tunable mechanical stiffness. Stiffness modulation is achieved through inter-unit jamming, induced by boundary force control, allowing flexible adjustments to the global structural stiffness. A comprehensive experimental analysis was conducted to investigate the stiffness evolution of CMMs with various unit configurations under varying vacuum levels. The results reveal a strong positive correlation between vacuum level and structural stiffness. Furthermore, due to geometric constraints stemming from the interlocked design, the CMMs exhibit pronounced double-sided asymmetry. Among the configurations tested, auxetic-based CMMs (A-CMMs) demonstrate the most significant stiffness enhancement under identical vacuum conditions, followed by compression-torsion (CT-CMMs), microcrystalline (M−CMMs), and spherical-based CMMs (S-CMMs). Practically, the integration of rigidity and flexibility within these CMMs allows them to be embedded into the outer load-bearing structures of vehicle wheels. This allows transitions between high stiffness (for load support) and low stiffness (for obstacle negotiation), providing a novel solution to the limitations of rigid wheels and enhancing performance and durability in diverse environments.