Tire Pressure

Newbie questions here:

How much pressure difference is there between an unmounted and mounted tire assuming the same tire is being measured?

If a tire's pressure' is measured lets say 10 times in a row, how much pressure will it lose from leakage?

Thanks in advance.

Let's be real precise in the terminology:

Unmounted tire = tire not mounted on a rim

Unloaded tire = tire inflated on a rim, but not touching the ground.

The difference in pressure between a loaded and an unloaded tire depends on the amount of load being applied. Typically the difference in pressure is between 0.1 psi and 0.5 psi.

You can verify this yourself, but you will need a gauge that measures in at least 0.1 psi increments.

Measuring a tire's pressure does indeed result in a loss of a small amount of air. However, unless you have a bicycle tire - which contains very little air volumer - you have to lose quite a bit of air to have a detectable change.