As Duc already pointed out, low pressure in a tire is better for sand. You really need to sort of float on the sand. Too much of an agressive tread will really cause you grief as it will dig in and down too quick when you slip and get you stuck. Years back when we were allowed to run on the beaches and sand sune areas in the Florida Panhandle, we always used regular street tread tires deflated to as low a pressure as possible and still retain themselves on the rims. All the rednecks with their giant mud and gumbo off road tires were always getting stuck, but my set of just about worn out tires worked fine. Biggest problem is the rolling friction of sand on the tires, so don;t underestimate its potential to give you a fit. Low pressure high floatation solves 99% of these problems.
Another item with running in sand, it allows sand to get in between the rim and the tires bead, when you run them at a low pressure, and this can eventually eat uyp the bead or sealing area of tires. I eventually bought tires especially for sand and they had a lip or extended piece of rubber that contoured over and around the wheels lip. This prevented most sand from getting into the bead area. Desert type sand is not like a beach type sand. Two different ball games.