Would putting 26-12-12 tires & rims on this how will it affect my on demand 4 wheel drive sensing? The 20% rear slip before engaging the front? Was going to keep stock 25" fronts.

 

as long as u keep the fronts and rears the same diameter.. in this case,
you're going from 25 fronts and 25 rears to 26 rears.. you'll need to go with
26 fronts also to make sure you're within the 18-22% required for
proper 4wd engagement....if u don't keep the balance between front
and rear, you could cause the rear not to spin fast enough to
properly engage the 4wd...also your front end would nose dive
a little quicker and ride lower(which to me is uncomfortable) if u
kept 25 fronts and changed to 26 rears..