any recommendation..?

Probably around 35 psi. You don't want to go too low with low-profile tires, or you make the wheels vulnerable to damage.

MB sticker for 2003 S600 with 18" non-Sport wheels says 28/29 for regular driving, 32/35 for fast driving.
I run mine at 32/35, but the 28/29 feels more like stock 16" wheels' ride.

thanks for the reply.....^O^

with 18 amg wheels. The stock dunlops say max pressure of 51 psi. I run 45 for now.... Hope not to bend a rim.