I have no earthly idea what kind of tire pressure I should be running on my rally cars
Try 20-25 lbs, depending on car and suspension setup. Less air helps absorb bumps and shock, which is a lot of what a rally car or off-road car has to face.
Take a look at the car you were offered for your first dirt race and see how it was set up by Playground’s car handling team as an ideal rally-spec car tuned up to S1 class.