Wheel diameter differences when using a wider rim

[Firestone]

Does anyone know how much rim width affects the height of a tire? For example if using the same 4.00 tire on a 18x2.15 and 18x1.85 rim, means that the wheel with 2.15 rim is smaller in diameter right?

 

[Wolfe_11B]

Not necessarily, it depends on how the tire is constructed.