What kind of Spark are you driving? The "Spark Z06"? My car has unresponsive, regressive steering to begin with. And as far as "weight bias" goes. You can feel how slow the rear end is to come around a corner because it's barely getting any rear end grip! Even for a FWD car the front tires are wearing at a comparably alarming rate to the rear. (Yes, I understand the front tires wear faster than the rear in a FWD car, however, the difference should not be as significant as it is at 8,500 miles....I shouldn't have to rotate the tires every 2000 miles or less)
You're assumptions are base