Tyre pressure for 1997 UrS6 Avant?

[Andyh-R6S]

Resurrecting my UrS6 Avant after a few years of no real use and I am going to replace all of the tyres with Goodyear F1’s. Does anybody out there know of or have a similar tyre fitment to my car that can advise me on a good normal setting for the tyre pressures? (For me and one other person in the car only.)

I have 8.5*18 wheels with rather old Dunlop Sport 9000 255*35 tyres fitted that will be replaced.