On Tue, 26 Dec 2017 23:09:02 -0800 (PST)
harry wrote:

The correct way to do it needs a contact thermometer.
When the tyre pressure is right, the temperature of the tread is the
same across the width of the tyre (measured immediately after
running.) If it's hotter in the middle, it's over inflated. If it's
hotter at the edges, it'sunder inflated.

I know racers do it that way, but it's not very helpful for our typical
trip to the supermarket and back.