Mike’s tire pressure numbers are a nice average to go by.
I get even more anal about tire pressure using a long built up experience in sand running. How tall is your sidewall? The taller the better for deflating.
That’s why i still ran 16 inch wheels on my 2001 Dodge Cummins: lots of sidewall for deflating. It’s all a feel of the surface you are going to negotiate; the weight of your TC; how hot the day is; how good your air-up device is; how wide your rims are. Why it that? There is sand and there is sand. I’ve tried over the years to take a measure of how soft and/or bottomless the sand is.
Tires now-o-days are very tough compared to tires 30 years ago.It’s very difficult to injure them.
I’ve driven all day in our old Lance/Dodge setup with 10 inch wide super single steel rims on the rear and 7.5 in. wide stock steels on the front.
front tire pressure: 28 pounds
rear tire pressure: 20 pounds
Why the discrepancy? The wider your rim is the less actual air pressure you can use for the same, “squat” or sidewall bulge. Also, when using very stiff truck tires, sometimes you have to go even lower. You just don’t want to pinch the sidewall on a rock.
I’m not sure yet how low to go on our new Ford’s stock 18×8 inch wheels. I suspect a good trail running pressure is: 28 front/30 rear. I’ll be able to tell once we start letting air out at the trailhead of El Camino del Diablo.
You just need to keep your eye (hand) on how hot the tires become. That means driving slower than you think to keep the temp down.
Hands on experience is better than anything I could contribute.
2020 Ford F-350 XLT FX4 4WD SRW SB SC 7.3L Godzilla Gas TorqShift 10R140 397 amps dual Alt dual batts Frnt Dana 60; Rr Dana M275 E-locker 4.30's 4580/4320/4066# payload 7243# curb wt. 11,300# GVWR 5-er prepped. 2020 Northstar Laredo SC, 12v compressor fridge, cassette, 320w Solar sub zero insulation.