Grip is the total force a tire can transmit between the vehicle and the road surface, in any combination of lateral, braking and acceleration directions. It comes from the tire’s friction coefficient multiplied by the normal force pressing it to the road, and because a tire’s coefficient falls slightly as load rises, the same axle produces more total grip when the load is shared evenly between its two tires than when it is concentrated on one. The available force is bounded in every direction at once, a relationship visualized as the friction circle, so force used for braking is not available for cornering. Grip is described as mechanical when it comes from tires, suspension compliance and load distribution, and aerodynamic when it comes from downforce, and the two respond to different variables and dominate at different speeds.