What is this circle? Whenever there is a thread I find there is a circle as well.
Is your Max Dia int.. of your thread.
Major diameter of the thread
This is how cosmetic threads are represented in 3d model and in 2d drawings, they're represented as dotted line. Please refer to a machinery handbook and all your issues will be resolved. This is not related to SOLDIWORKS but general engineering.
..circumferential annular tear?
Major diameter of the thread