tire sizes

[Andrew Buc <72220.443@compuserve.com>]

 >  I  recently acquired an 87 5kcstq that runs 205/50/15s on the 
 > front  (firestone firehawks) and 215/50/15s on the rear (same tire)
 
This brings up something that's been in the back of my mind. I've heard that 
putting tires of different rolling radii on a driving axle will overwork the 
differential, and that certainly makes intuitive sense. So, will mismatched 
tires front/rear overwork the center diff? Of course, the center diff has to 
work any time the car isn't moving in a straight line, even with 4 identical 
tires, so maybe this is apples and oranges.
 
--Andrew Buc, Seattle, WA; Internet: 72220.443@compuserve.com