Ya know reading this all just made me realize what we're talking about with a tire. At first, I thought, "There's not a solid steel band, so how can steel belts help?" Then I realized, if you had a flat cable in the middle of the tire, and its circumference was exactly 25" with no ability to stretch out, and the circumference of the cables near the sides of the tread on a tire were 25" circumference with no ability to stretch, you'd have no way to make it "Bulge" in the middle and wear out the center first. The tire will hold its cylindrical shape because the steel belts don't stretch.
Sort of reminds me of another thing that has no bulge because of its steel belts.
Same principle, just shorter, smaller, rubberier, and less corny.