Mixing New & Old Snowtires on Quattro

[Steve Sherman]

Just got a flat in one of our Happa 1  (looks like  a sidewall
failure).  These were last years tires and probably have 1/2 their tread
left.

So my question is can one safely mix one new tire with a slightly larger
diameter (due to more tread) with the other old ones on an 86 5KCSQ?
Does the center diff take care of the bigger diameter, or will one be
causing bad wear in the drivetrain?

Anyone know?