If it's a dedicated beach vehicle, I would recommend an off-road tire for better traction. While street tires work OK, especially if there's been some rain, the off-road or mud-type tires will give you better traction without worrying about lowering air pressure. If the current tires on the vehicle are not worn, just use them up. When it's time for new ones, then get the mud tires.
Tire noise is sometimes mentioned as a downside. However, if you are choosing a lightweight vehicle like a Trooper, Pathfinder, 4-Runner, etc., mud tires are not very noisy on the road.