Is there a way to calculate the correct bicycle tire pressure? I have 57-559 (57 mm width, 559 mm diameter) / 26"x2.125" tires.
I weigh about 95 kg / 210 lbs.
The tire's sidewall shows a single pressure value of 300 kPa / 43 psi.

However, this calculator shows that given a fixed tire size, different rider + bike weights would have different optimal tire pressures.

Is there a way to calculate such an optimal pressure?
I looked into it and found this PDF: 2004, Berto: "All About Tire Inflation",
where the optimal tire pressures were found experimentally from a Tire Drop test, where


  Tire Drop is the distance that the tire sags under the weight of the rider and the bike.
  For a given tire size and load, the optimum inflation pressure for comfort and rolling
  resistance produces a Tire Drop of about 15% of W (the Section Width) or about 20% of
  H (the height from the ground to the rim). 


For my case, that document shows the minimum tire pressure somewhere around 25 psi / 172 kPa for a 26"x2.125" tire.