The center of gravity is the balance point of the entire vehicle. Its actual position depends on location of the major components. It is always located above the road surface, and between the tires.
When a vehicle is cornering, this is the point through which all centrifugal force is assumed to act.
Its position is determined by the load carried by the front and rear wheels, that is, by how weight is distributed. In a 40%-60%, fore-and-aft, weight distribution, 40% of the weight is carried on the front wheels, 60% on the rear, and the center of gravity is closer to the rear than the front.
A weight distribution of 60-40 has the center of gravity closer to the front than the rear.
Lateral weight distribution can be expressed in the same way.
The height of the center of gravity is determined by the height of the mass above the road surface.
Every vehicle has static weight distribution, whether it is at rest, or traveling in a straight line at a steady speed. This is changed laterally by centrifugal force when the vehicle is turning, and in a fore-and-aft direction during acceleration, or braking.
During cornering, centrifugal force puts more weight on the outside wheels.
Acceleration puts more weight on the rear wheels.
Deceleration, or braking has the opposite effect.
In a turn, centrifugal force tries to push the vehicle away from the corner. This is resisted by the cornering force of the tires.
The tires have slip angles, due to the cornering forces acting on them, and since the cornering forces at front and rear may not be equal, the slip angles at front and rear can be different too.
With the center of gravity closer to the rear, the rear tires carry more of the weight, so they operate at a greater slip angle than the front tires. Larger side forces act on the rear tires, which causes greater tire distortion.
This condition of higher slip angles at the rear causes oversteer.
More weight on the front tires means they corner with greater slip angles than the rear.
The vehicle is then said to understeer.
With equal slip angles at front and rear, the vehicle is said to have neutral steer.
Radial ply tires generate much higher cornering forces than cross-ply tires, which is why the 2 tire types should not be used on the one vehicle.
Slip is also influenced by inflation pressures, so manufacturer recommendations should always be followed.
Source: CDX Global
