I'm not sure what you mean by "rolling speed of the plane", "it's forward movement", and "speed of the treadmill". The phrase "rolling speed" sounds like it refers to the component of the plane's forward motion due to the turning of its wheels, but that's not a coherent thing to talk about if one accepts my assumption that the wheels are uncoupled from the plane.
Rolling speed = how fast the wheels turn, described in terms of forward speed. So it's the circumference of the wheels multiplied by their angular speed. And the wheels are not uncoupled from the plane they are driven by the plane. It was only assumed that the friction in the wheel bearings is irrelevant.
Forward movement of the plane = speed of the plane relative to something not on the treadmill. I guess I should have called it airspeed, which it would be if there is no wind.
Speed of the treadmill = how fast the surface of the treadmill moves.
And that is ...
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