Tire size diameter installed smaller?

[schildkroete]

I've checked three sizes of mounted tires I have and they seem to have about a half inch smaller diameter than the sizes listed for new tires of each size.
Is this typical so I can predict the installed height for new tires? Thanks.

185 65r15 on 5.5 -24 in. near new
165 80r15 on 4 -25 in -worn
155 80r15 on 4 - 24 in- worn

tread wear was taken into account.

[ps2375]

Not all brands are the same, close but not the same.

[schildkroete]

I was thinking about if the same tire would could be a different diameter off the the rim (larger) than on.

[ps2375]

[911pickup]

I would thing the difference in diameter between mounted and unmounted would be negligible.

[easy e]