Car Physics Unity Github [portable]
Design a "Wheel Prefab" containing a "wheel holder" for rotation and the actual graphic. This allows you to easily swap models without breaking the physics logic.
While not always a standalone GitHub repo (it is often part of Unity's official sample projects), the is the baseline for realistic physics. car physics unity github
For developers who want high-fidelity simulations, the TLabVehiclePhysics Repository is a premium open-source alternative that introduces custom tire logic. Design a "Wheel Prefab" containing a "wheel holder"