Is contact patch area governed by A=W/P
Assuming a 200 pound rider+bike+clothes+load and a tyre pressure of 100 PSI, and a nice even 50/50 weight distribution, then each wheel is supporting 100 pounds and should have a contact patch size of 1 square inch.

You could empirically measure this using a scale and a dry piece of paper, and a slightly dampened tyre.   Moisten the tyre and use its "footprint" on the paper.  Do the same with the rear wheel.  And then draw around the boundary with a pen.
Perhaps a dusting of talc powder on the tyre would work better than water.