Another Tire Size Rant/Warning

[dddd]

Originally Posted by spoonrobot

...Also keep in mind that the casing is a fixed dimension and using wider rims to get a wider tire often leads to a much shorter tire. I've got a pair of 38mm gravel king slicks that are great but never quite gave me the performance/comfort I was looking for when mounted on 25mm internal rims. Turns out they were running 40mm wide but only 33mm tall so the pressures I was using were all wrong.

Within the range of rim widths that I have used, a wider rim consistently made the tire taller.
I had read something in the Rivendell Reader many years ago suggesting exactly what you said, but I only found the opposite to be true when I measured tires mounted on different-width rims.
It seems that as the rim becomes extremely wide, approaching greater inside width than the tire's outside width, that the tire's height would shorten, but some of the rim/tire fitments that I checked did have relatively wide rims and the tire's height only grew with increasing internal rim width.
If we measure an inflated tire's width and height, it's normal for a tire to have much shorter height than it's width if we measure from the outer edge of the rim out to the tread surface.
A knobby tire, or a commuter tire with thick gel layer under the tread, may have a much taller profile.