It really depends on where you are going and the type of sand/beach. If you are doing loose sand you'll want to air down to 15 to 18psi any lower you risk losing your bead. If the access to the beach is hard pack you may not even need to air down, but it doesn't hurt. You do want to have at least a portable air compressor to air up when your done, make sure the cord is long enough to reach all 4 wheels. You probably have a power port in the rear of your jeep too.
2011 JKU Sahara; Sahara Tan, Leather, 3.73, Auto, Hard/Soft Top, SpiderWebShade, Dead Pedal, Skid Row Foot Pegs