to add, with slight correction. Auto is the preferred section.
your tag does not lift. In auto, when you select reverse, the tag air bags dump the air. that lessens the drag and helps the Lock Straights to straighten your tag wheels as the tag wheels rotate.
The disable, will eliminate the above. Still works, but you will have much more drag on your tags in reverse.
Manual, you have to hold the switch to manually dump the air.
as stated above, if the drive axle is spinnig, you can manually dump the air in the tag axle for 'hopefully' better traction for the drives.