Edit: 10/26/15 – I’ve removed the link to the google Doc. The locked fields didn’t work, and people have defaced it pretty severely. Download this XLS file for your own use: Tire Pressure – salvaged doc
You can use the tire pressure Excel file to calculate pressures for different kinds of bikes. Put in your weight and tire width, and it gives you the optimal pressure for Road, Cross, Mountain Bikes, Low-trail randonneur bikes, Fat Bikes and Triathlon bikes.
You can fudge the numbers based on your experience, tire casing, riding style, and road surface. More info about the pressure calculator.
There is also an Android app available. You can save your bikes and easily access them later. You can even do custom calculations for cargo bikes, which the doc doesn’t do yet.