my tractors are 4x12 and are extremely heavy, I can see grass damage after one day with five chickens, so I move mine daily (two days at one location is max.), I tried moving them with a tractor with front end loader and that did not work so now I use a two wheeled dolly similar to the ones used to move a refrigerator but much bigger tires, they run me over going down hill and I need help pulling them up hill, I have aprons of galvanized wire on all four sides that fold up for moving.