Can you use texrotate on a rectangular texture?

I'm having trouble getting it to work correctly.

In this example texture, would the center point (green) for the texrotate animation be x =.25 and y =.50 assuming i want to rotate the red dial?

I am animating the red circle as if it were a number dial like for the ALT. The black squarish object (lower left) would be the window object that the red number texture rotates through.

This used to be a square texture 1024x1024 and the red dial would have been in the lower left quadrant. Its center point was x = .25 and y = .25 and it worked correctly. What I don't understand is that for this new 1024x512 texture x = .5 by y = .5, while still wrong, actually appears to be closer to the correct uv coordinates than what I thought it should be at x = .25 by y = .5.

Any suggestions as to what I am doing wrong or not understanding?