What are the ideal alignment specs as far as camber is concerned? Need the best compromise for handling and treadwear......

 

Street tires are designed [optimized] for negative static -0.5 degrees camber max.

A good indicator is the EXACT midpoint of the wide oem camber range;

Unfortunately the suspension camber gain curve as the body rolls may not be sufficient to hold this -0.5 as the body rolls depending on the steering angle.

Camber and caster should be equal as close as possible [no more than 0.2 degree] side to side......otherwise the car will drift to the left or right.

 

depends on what you use your car for. if you're driving a lot of curves, more negative camber will reduce wear on the outer edges. and you i don't think you can adjust camber on a stock z.

on my miata, i have -1.2 in the front, -1.5 in the rear, but that's geared towards fun driving and track days rather than commuting. i'll go more negative in the front next time i align it since it wasn't as tail happy as i thought it would be at the last track day. slight toe out in front, toe in in the rear, caster maxed out (just over 4 deg i think)

 

The problem is the more negative camber the less effective the tires are in staright ahead braking.
He asked for "compromise for handling and treadwear".

 

As far as Camber -1.5 is about as much as you want to go without getting really excessive tire wear. I would suggest going 10% more camber in front than rear due to most of the weight of the car being in front and you will want good bite from the rear from a stand still.

As far as Toe - for straight line front and rear - toe in slightly, for turning front toe out and reear toe in both slightly (1/32")

The best thing to do is buy a cheap pyrometer (<$100) - learn how to use it and it will tell you what the ideal set up is for you type of driving!