I’ve been driving in the sand most of my life here in SOCAL- Glamis. 75% of my off-roading is in the sand or sand based, that being said beach sand is usually wet underneath which gives you better traction but the goal is to float on top of the sand which is why you air down so you could get a bigger foot print on the sand. Some people say they never air down which is fine but you will need more momentum to stay on top of the sand, airing down lets you cruise on top of the sand without have to use momentum to keep you there.
Dry sand and wet sand are two different beast, fine sand and course sand are two different beast. You need to know what your driving in to know how your going to setup your tires.
I usually start at about 12-15lbs and if you need more floatation go to 10-12lbs but the lower you go your driving habits need to change as you will need to be aware the you could pop your bead off the tire( so no doing doughnuts in the sand).
MY NEW JEEP- 2011 JEEP JKUR, Body Armor front bumper, Warn XD9000I winch, Synthetic winch line,XRC Rear Bumper W/Tire carrier, OBA W/1Gal Tank, Terafex 2.5in spring lift, Bilstein 5100 shocks,GY 315/70R17 Duratracs, 4.88 G2 gears, Cobra 75 CB
MY OLD JEEP-1999 Wrangler Sport 4.0L, 4" Pro Comp Lift, 33" BFG's, 8K winch, SYE, Viking soft top, onboard CO2 and all the recovery straps and equipment