Measuring the mounting pattern of a hub is shown in this figure, with the lug bolts touching the frame and on the right side of each leg. If the hub center gets in the way of the legs, you may line the lug bolts up with a pair of the reference marks on the legs.
Just remember to keep one lug bolt inside of the legs and the other lug bolt outside of the legs. The mounting pattern is indicated in trade size where the adjustable leg meets a graduation mark. For more information click on the picture.