Roll Stiffness

Roll stiffness is the mechanism that suspension designers use to control the vehicle's roll (rotation about x-axis).  The units of roll stiffness are Nm/deg. The inertial force at the vehicle's c.g. creates a moment that attempts to roll the car's body, but the springs of the car counteract it.  The formula for roll stiffness is 0.5*(Ride Rate)*(Track Width)^2. Anti-roll bar stiffness adds to roll stiffness. Here is the derivation: