I guess I could accurately measure the lever arm, and then use the OEM specs to calculate the amount of arc possible and get a measurement og axle movement front to rear.. But since each axles arcs are independent of the other end, they may be at different points of the arc when installed, hard to determine, and also very hard to move.

Additionally the near 1/2" I measured was between the two axles compared side to side, so its possible each axle on one side was 1/8" to its opposite extreme away from each other axle, and the other side was 1/8" closer together, giving me my 1/2"measurement. How much of that 1/8" ? was arc travel and rubber misfit, I don't know.

Main thing, don't measure from the axle centerline when brand new and installing is my lesson.

Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.