Originally Posted by TejanoTrackie

Use the following formulas to determine proper tire pressure as a function of rider weight and tire section:

Tire Width=20: Pressure(psi) = (0.33 * Rider Weight in lbs) + 63.33
Tire Width=23: Pressure(psi) = (0.33 * Rider Weight in lbs) + 53.33
Tire Width=25: Pressure(psi) = (0.33 * Rider Weight in lbs) + 43.33
Tire Width=28: Pressure(psi) = (0.33 * Rider Weight in lbs) + 33.33
Tire Width=32: Pressure(psi) = (0.17 * Rider Weight in lbs) + 41.67
Tire Width=37: Pressure(psi) = (0.17 * Rider Weight in lbs) + 26.67
Front Pressure = .9*Rear Pressure

For example, the OP weighs 185 lbs and uses 23mm wide tires, so Rear Tire Pressure = 0.33 x 185 + 53.33 = 114 psi. Front Tire Pressure = 0.9 x 114 = 103 psi.