265/35/19 F / 285/35 R effects on understeer and vdc?
 

Anyone ever ran this setup? I'm on OEM sport rays and wondering if it would help with some of the understeer our cars have.

Tire calculator says that would be 26.30 diameter front, and 26.85 rear.
Compared to stock, this is a -1.57% (fast) change in the front; and a +1.03% change in the rear (slow). Is that going to upset VDC?

I was looking at RE-11's and curious if anyone had tried this setup or something similar with more meat in the front. It seems many in the 370 world run a 3 tire size difference in stagger, opposed to the 1 or 2 that is commonly found on 350s.

I ran 265/35 285/35 in RE11 for 15k miles, no VDC issue.

I'm running 265/35 & 305/30 on Sport Rays...no issues

As for your size choice...why not something like 255/35 & 295/30
identical sidewall, radius, diameter and only minimal circumference dif (-0.2 in the rear)

even 255/40 & 285/35, the dia. dif is 1/10"

^ because OP is trying to reduce the stagger to improve understeer.

Could you run 285/35 square? I have ran this setup for autocross and loved it

Having run a 265/285 setup on my Z for 10k miles, They help with turn in, but they are bulging on the front sport rays. I will be going to a 255/40 on the front next time around, as well as going back to a 275/35 in the rear. They wear the same as a 245/275 setup, although these have been killed by bad bushings in the FLCA's that is causing drastic dynamic toe wear.

What suspension mods do you have? Decreasing the stagger would definitely help reduce understeer, but a good set of sway bars can also do wonders. I run 265/35 and 305/30 RE-11s with Eibach sways and the Z turns in quite nicely.