Centerline is about 6'6". I have had chickens in simular tractors now for 2 years and never had the first critter burrow under them. Now that could change because I am in a rural area that has coyotes, coons, foxes, and bobcats. The first one I built I was worried about it and put a chicken wire floor in it . It
quickly cakesdup and became a problem. After awhile with no issues I decided to take my chances and so far so good. I may add some type of skirt to it this summer.