Here's the detail from the 2008 X5 Owner's Manual that says
1. 32 psi in front and
2. 35 psi in rear
for all 20" wheels for X5's with third row (whether 3.0si or 4.8i and with or without sport package).

If you only have two rows of seats, it's 32 psi all around...

Attached Images

 

__________________
2008 X5 4.8i | Wheels: Summer> style 336 20" RFT; Winter> style 214 Ferric Grey 20" RFT | Aero kit | ESS E-Flash tune | V1 | LCI Rear Tail Lights | Coding completed | Engine replaced at 90K