For all tyres the handbook says:
Normal operating conditions, front 28lb/ft (1.9 bar), rears 38lb/ft (2.6 bar)
Vehicle fully loaded to max gross vehicle weight, front 28lb/ft, rears 46lb/ft (3.2 bar)
I've just replaced my BFG AT's with Grabber AT2's, and am having a fun time trying to find a 'comfortable' pressure to run them at for A road/motorwy driving.
The pressures quoted above are for a Disco2 ( :doh:), Defender pressures are similar, fronts are always 28lb/ft (except the 130 which runs at 44lb/ft), rears are 35, 40, 48 or 65lb/ft depending on whether you have a 90, 110 or 130