Not sure on a drag radial, but I use this method on a regular slick.
The best formula is to start higher PSI and find your sweet spot as it relates to hooking off the line and ET. Lower PSI will obviously help you to hook better but you will potentially lose MPH which could effect ET. You have to find your ideal happy medium which will yeild the best timeslip.
Not sure if people screw in a drag radial, never really paid attention, I have my ET Streets and my slicks screwed in to the bead as at the track my car turns the tire on the rim (or rim on the tire?) and I got tired of constantly getting out of balance.