My Z has been dyno tuned and I am getting ready to change the rear to 4:10's and the rear tires from 16's to 17 and put 315x35x17 Nitto's. Will I need to have the PCM changed???

 

Yes if you want a correct speedometer

 

You'll need to change the tune for the rear gears, but the tires should be within .2" of the same overall diameter so you shouldn't have to change that. Any speedometer error caused by the tires would be minimal.

If you're planning to run those 4.10s in the stock 10bolt, might as well buy a couple of sets. My understanding is that the higher the number the thinner and easier to break they get.