roll stiffness calculation of trailing arm air suspension

Please sharpen your point

I assume you mean you need some form of calculation to work out how stiff an anti roll bar you need. (sometimes known, incorrectly, as a sway bar) Firstly, have you worked out where the roll centre is? Depending on the geometry of your suspension, this could be 10m underground, and you won't need much at all. I think this highly unlikely, however. Have you got very soft air suspension? if you have, you can go quite hard on the roll bar, and vice versa. Please bear in mind, you cannot couple both sides of your suspension together like this with an air derived device, the air will compress and allow too much movement, making for a very 'woolly' fell to the handling. The action of a roll bar can have significant effects on under steer and over steer, so be cautious!