by creaky on Wed, 18 Jan 2017 8:45 +0000
'Safely' ? Depends how fast you are travelling.
Assuming that this is not an LT construction I would probably start with cold pressures of around 34 road, 28 gravel, 20 sand/mud/rocks. From there you work down as required to suit conditions but remember at pressures below 25 there is a chance of ripping the bead off the rim if you do not drive appropriately i.e. no 20psi at 100km/h on the highway and no 15psi at 80km/h on the beach.
If you are stuck with wheel spinning in sand then drop 'em as low as you need to go to get out, even 8-10psi !! Just don't go anywhere till you pump them up again.