Two up for road use, and have done for 5-years now, 39/37 psi front to rear and that's with either 255/30 fronts and 235/35 rear MPSS summer tyres or 235/35 fronts and 235/35 rear Vredestein winter tyres. Having fitted both sets 'new' I was able to monitor the wear across the tread and found these pressures provided the most even wear across the tread, and best ride.
And I found these pressures best for the OEM Continentals, too.