I use the pressure calculator at zipp.com. The results aren't said to be the fastest, AFAIK. The issue is often how smooth or rough the asphalt is. One pressure is never perfect for all conditions. I ride tubeless with hookless rims. At 135 pounds, I never exceed 60 psi with 28-30mm tires. I have a lot of chip sealed roads, so I tend to use lower pressure.