It does not correlate to the rear torsion beam roll part stiffness, However it is correlatable in Front Stabi Dia/Span ratios.
Could some one explain why ?
Roll Stiffness Calculation is Based on
Roll Stiff = Roll Moment / Roll Angle
Roll Moment = Tread / Load Change Fz
Roll Angle = Tan-1 ( Change in Wheel center Z / Change in Wheel Center Y) * pi()/180