[Moppie]

Well as long as the pressures remain with in the spec of the tyre, then it will have the same effect as stiffening the suspension.
i.e. harder at frount = understeer.


However the correct tyre pressure should allow the tyre to maintian full contact with the road at all times.
This may mean you are unable to use it to adjust the cars balance.
basicly if you get the suspension set up right then you can run the ideal tyre pressure.
If you dont get the suspension just right, then you can adjust the tyre pressure to compensate at the expense of total grip.