as the anti-rotational force of the gear and the C of G would all effect the resultent required force.
Does the gear exert anti-rotational force?
On a tricycle, the main gear is behind the CoG (or else the plane would fall on tail) and therefore the rudder is closer to main gear than CoG. This means that the main gear ought to exert a torque tending to rotate the plane. In other words, for exact same rudder sideforce, when the main gear is off the ground the plane would tend to slip sidewards and resist yawing, while a contact between the main gear and ground would resist sidewards slipping and cause the plane to yaw instead of slipping.