Think you'll find that answer like should I use synthetic or not. my 91 is my DD when i need to go to town which is 15 miles each way. Cause Im lazy I leave my tires at 16 cause I off road several times a week. Would I use that pressure if im freeway flying...NO. back to 25.
If you play around with some low pressures if you have time post your results. my 31's at 16 still only give about 70% of the tread width. Wouldent want to go any lower on pavement but on dirt Id like to go lower. Just dont wanna pop a bead off 40 miles from home.
I forgot all about the chalk test.
Last time I heard about that was when I was in High School auto shop!
Too low of pressure off-road with a Radial will likely break a sidewall before it comes off the bead.
That's why I don't, and won't have radials on a Jeep. (but mine isn't a DD)
Running bias-ply tires I can't recommend pressures, I run my TSLs @10psi street and 4psi off-road.