How many psi are you guys keeping your front and rear tires at with the 19" rims?

I always have my tires checked while servicing the car, I bought some wheels with tires in Europe for my Wifes Audi A4 and they filled them with (correct me if i am wrong) nitrogen? anyway I notice that they stay inflated much longer than the tires on my X5.
It is a very common thing in Europe to fill the tires with anything other then just air...they also use green caps to signal that one shouldn't refill with "regular" air.
Anyone knows what i am talking about?

I know what you're talking about, not sure if it's nitrogen though. The reason they use something other than regular air is that the gas is more stable, and less susceptible to the pressure variations that air is to from temperature changes. Then again, I could be talking out of my butt...

Anyway, still looking for a good pressure to bring my tires up to. They are the stock Turanza tires on the 19" SP rims.