I was surprised you couldn't find them in either manual, made me have a look myself as you say, not there. So I looked in my Volvo owners handbook, page 67.
Front 1-3 persons 26, full load 27
Rear 1-3 persons 28, full load 41
For long-distance driving at speeds near that of maximum for the vehicle, pressure should be increased by 4.5psi.
Love the the terminology of the day
This all of course refers to the original tyre size of 165/80/15