"Setup":
nearly completely stock RX8 R3, even alignment (may adjust before event hopefully...)
18x8 OZ race wheels, 245/40/18 Hoosier As (cheap takeoffs, 6-8 HCs)
Weight around 3050-3100 with driver last I weighed it.
Track usage - NASA Time Trials

What kind of ballpark starting pressures should I consider?

I'll adjust based on feel / pyrometer / etc but I don't even really know what would be "close" beyond pulling something out of my butt. My experience is mostly with strut cars that roll alot and are hard on tires, so this "proper suspension design" stuff is all new to me... not sure how much lower/higher to start to account for that. I'm usually running around like a chicken with my head cut off at events running two cars and trying to manage the group I'm in charge of so I would love to start out closer to the sweet spot than a wild-*** guess would get me.

Thanks in advance!

 

I did not have a stock alignment but I ran 39F and 36R on 285/30-18 A6's

 

you started with 39? I always shoot for 39 hot not cold. i start around 34 cold and check after a run and let out till I get 39 hot.

 

Nobody ever says what temp they check pressures.

I run 36 psi @40deg front and rear or 43-44 hot after run on track.

That's on a soft Hankook Ventus V12 225/40r18.

Rear camber -1.65 instead of -1.9+ measured as stock.