Well, in theory, you should increase the pressures as the sidewall reduces.
HOWEVER............................................
The standard set up on 205/55 16's (2.1 BAR @ F/1.9 @ R) & is set up to slightly lean towards the safer understeer (higher pressure up front), but I personally like 2 BAR (29 psi) all-round on my 225/40 18's.
