Check this:

http://www.vintagebicyclepress.com/images/TireDrop.pdf

I can add to this and say that on asphalt any pressure over 90 psi is detrimental to rolling resistance, so you need to choose a tire size that allows your weight to be carried with no more than 90 psi. Approximately 2/3 of the weight is on the rear tire, so the rear tire needs to be a larger diameter than the front tire. The reason for the 90 psi limit is that, believe it or not, higher pressures tend to deform the asphalt, which is not good for rolling resistance. Concrete surfaces can take a higher tire pressure. The use of 130 psi road tires is a practice that has already been proven wrong and I think the knowledge of this will seep down from the HPVA racers to the road racers in the next ten years.