Front tire matching 2005-2012

[curvecrazy]

Hi.  I’m new here.  Quick question about tire matching.  The new AWD cars require tread depth tire matching in order to not mess up their AWD systems.  
I have an 05 Pathfinder LE 4WD version.  This has the drive selection for 2WD, AWD, 4WD and 4WD LO.  
I don’t use anything but 2WD.  I understand that, in 2WD the rear wheels are active and that it’s best to tread depth tire match that rear axle.  But, since the front is not engaged, is tread depth tire matching required in the front if only 2WD is ever used?  
I know best practices and all that, but I have a bad front tire and the other side is well worn.  I was thinking of just running the new full size spare.