Tractor, truck, car or lawnmower,......driving on pavement, grass, gravel, glass or a bed of feathers,...... "properly" set up and "aligned", (and yes "toe-in" set) and proper air pressure, etc....... your tires should wear "evenly"!!! If any of these factors is slightly off,...expect UNeven wear.
And Yes, certainly, of course,...you can switch 'em around till your blue in the face to ensure that the UNeven wear happens on them all for as long as you can encourage them to last in that abnormal state,...if you wish,...and of course that is the personal choice of the owner of that piece of equipment.
BUT,....as previously stated,...to get the longest use of the tires on "any" equipment, proper maintenance and careful alignment is an important factor!!
OK boys and girls,..that is my final lecture on this subject for this particular thread. Believe it or not, I'm not trying to be a "wise-guy" either,...but simply trying to help out,...with my two cents:..and you may "Take it or Leave it".
The very best wishes to you all,
. . . tug