I have Hankook K104's and I run 38PSI for city driving, in the hills ill just leave that but check that it hasnt gone down.
In the wet, in twisty terrain I up it to 42-43psi.
I keep even tyre pressures all around
As far as tyre codes
245/45/R17
width in mm/profile/diameter in inchs
Profile is a % of width, aka, the sidewall is 45% of the width in this case. Hence, larger wheels can be fitted with keeping the same rolling diameter by reducing the profile of the tyre.