Any input would be great. I currently have 225/40R19 in the front but want to go to 245/35R19 ultimately up front on my stock 19" Rays.
The 245/40R19 is kind of tall but comes that way from factory. Here are the differences in diameter. The 255's are about $80 more for what it's worth...
FRONT
225/40R19 26.1"
245/35R19 25.8"
REAR
245/40R19 26.7"
255/35R19 26"

Has anyone run the 255/35R19 in the rear and favored them over the 245/40R19?
I need to pull the trigger on these and figured bouncing this idea off of all of you would be worth a shot.
Thank you all in advance.

If you want to go wider, go 235/40/19 front and 255/40/19 rear. The tire sizes you listed are too short.

With your OE wheels you could easily run 245/40 (F) and 255/40 (R) or 245's on all four corners which works well and is more stable than the 225's out front!
Gary

I would advise against 245/40 and 255/40. I used to have this set up and it gave me VDC issues. I went back to smaller tires and VDC issues went away. You need height stagger between front and rear for VDC to be happy.

My issue is that I have a newer set of 225/40R19 on the front. I put them on when I first bought the car. In retrospect, I wish I'd gone with a 245/35R19 front. 245/40R19 is too tall for the front for sure. I still haven't made a decision and have some runway to do so as I am currently doing a Whiteline Bushing overhaul on my front end. I really want the 255/35R19 out back, they are about $80 more than running 245/40R19 but the 245/40R19 seems tall to me, even though it's the factory issued size.

Since 2006 I have been running 245X35/19 (F) & 285X35/19 (R) with zero issues on custom offset after market rims wider than OE!!
Gary