Thanks for all the help!
The curvature when I'm trying to create a shape where the inner ring doesn't have as great a circumference as the outer ring. @PixelPest in the gif example (thx btw) you gave earlier, that makes sense when both the outer and inner ring are the same size and you are creating something with parallel lines on top and bottom. However generally what I was trying to do was create something that pulled towards the center where, as @ESPR pointed out,
And that was what had always been my problem. In duplicating and trying to minimize the circumference (so that the ends taper in instead of being parallel) I always changed the curvature.
What I hadn't thought of that ESPR pointed out first (and PixelPest you put in one of your screenshot examples) was this
This creates a ring with both sides having the same curvature but the inner one being at a lesser circumference (so that the top and bottom taper in) and was exactly what I was looking for. In fact I really don't even need to expand it, I only needed a blocky shape so the overexagerated line works fine.
Thanks everyone! Had been bothering me for a while now and you all gave quite prompt and helpful answers (allthough my reply time could be improved lol).
And that's why they have different curvatures.
Yes. I was more thinking along the line of the same ratio of curvature. The inner and outer rings may curve different amounts but using the examples given above you can make it so that they are proportional. Like if you cut out a piece of pie and then only used the crust, that shape was what I was looking for. The inner and outer parts have different circumferences but a proportional amount of curve so they look cohesive.