seems that z owners with 17's have 225/50/17 front and 235/50/17 rear the diff in diameter is .39

I want 255/45/17 in the rears and want to put 235/45/17 in the fronts to hopefully reduce understeer, the difference in diameter is now .71

will this affect traction control?????
and will this defintely reduce understeer compared to a lot of others who have gone with
245/45/17 fronts and 255/45/17 rears=.36 diff in diameter which does not affect traction control but does cause the car to feel softer

thanks--tires are worn at 12K

 

I have used (4) 255/40-17 and (4) 275/40-17 at all corners, and currently have 255/40 front and 255/45 rear, all above combinations on my track tires, although I have used them on the street extensively also.

No issues with traction control or abs, but the understeer is definitely reduced.

 

Check out Kumho's in that size. I have them on my enth. and the diameter was closer then your .71. That seems closer to the diff in circumference on mine. I have no probs with TCS. Still comes on with slips but less often as the tires are nice and sticky. Does reduce understeer some too. They will track ruts in roads more, though.