Well, every tire/rim combo is a little different. I have 235/35/19 and i fill them up to 40 all around for my reg driving. They were down all the way to 25 when i just took the car out of storage.
Not sure what yours is "supposed" to be at. Maybe someone with the same combo can help.
Wait, i had 235/40/17 on my E36 and also had 40 in them.