Pressure fluctuates with temp, so although mine were ~3 psi below specified on door jamb plate when cold (i.e. having not been driven for a couple of hours), I left them that way because it was about 15F when I checked (maybe colder). Not sure if documented but pressures need to be correct at "normal" temps (e.g. perhaps "standard temp" used in science (i.e. 25C/77F). I'll check them again when it warms up. In any case, my X3 handles quite well (so far, no erratic handling).
2013 x35i (Space Gray, MSport, CW/CWII, DHP, Premium, Premium Sound, Technology, BMW-Apps)
Retired:'09 C300 4Matic, '09 GTI, '06 750i, '05 C55, '04 R32, '03 M5, '02 GTI, 01 M5, '00 M-Coupe, '00 540i/6, '99 M3 Coupe, '98 M3 Coupe, '96 328i, ..., '86 4000CS Quattro, ... too many to list