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      08-23-2013, 09:54 PM   #17
Lieutenant Colonel

Drives: 2013 M3 Coupe
Join Date: Sep 2006
Location: So. Cal

iTrader: (10)

It has to do with the load index of the 255/275 combo.

PSS and PS2 in 265/245 stock size has the exact same load index, but since the PSS 255/275 has higher load index, you actually need to lower the pressure a bit or the ride may get a bit too stiff and jittery. All the info is on

My door jam sticker says 35 psi front and 36 psi rear, and my calculation actually says we should run 32 psi front and 34 psi rear for the PSS 255/275 setup, very similar to what Malek has posted.