Spin out wheels have rails welded to the rim in a spiral direction. To move the tires in or our, you loosen the clamps holding the center portion of the rim to the outer rim, place a stop pin in the hole (several holes are drilled in the rail at various points) where you want the rim to stop. Then if you want to move the rim out, you put the tractor in forward gear and spin the tire till the inner rim hits the stop, then tighten the stops. To move it in, do all the previous but put in reverse gear and spin the tire.
It is a quick way to move the rear tires in and out on tractors with a fixed axle length. Larger tractors have an extended axle length that you have to slide the wheel in and out on after loosening bolts, jacking up the tractor etc. so they don't usually have any spin out rims.