actually negative camber is when the tops of the tires tip in...and you get negaitve camber when you lower a vechile..go look at the ricers..positive camber is the top of the tires tipping out, and this happens when you lift a vechile..(non S.A.)
and to counter act the crown in the road, you adjust the caster...
toe and camber wear tires out, caster does not.
but castor will cause the vechile to pull to one side or the other, and caster affects the rate at which your steering wheel returns back to center
so to counter act the road crown you run more caster on the passenger side, so it pushes against the road crown, and the vechile goes straight.
Allthough "technically" your not susposed to have your vechile go straight when you let go of the wheel..the road crown is there for A. water run off, and B. if you fall asleep, you will drive off to the side of the road instead of crossing over and hitting someone head on...