245/40/18 front, 245/45 18 in back?

I believe it drops the front tire + wheel diameter a 1/4`` or so. VDC should be ok, right?

How about steering feel? Any big difference in response to the skinnier 225`s? Heavier front end feel?

Does the extra grip from the front negate a lot of understeer? Some?

I`d like to stick a 255/40/18 on back (I have 8.5`` rear rims), but that size seems hard to come by in many brands.

 

That setup will mess with your VDC and TCS. I'm speaking from first hand experience. The aspect ratios must remain the same to avoid issues. You can fit a 265/40 in the back, and a 245/40 in the front. that shouldnt give you any problems.

 

I have this set-up on my stock Rays rims and it has never affected my VDC. The rear is still staggered in regards to tire diameter this set-up will be fine, and feels like it understeers less than the stock 225/45 set-up I say go for it.

 

VDC may not be happy with this set up. Yes the rear tires are taller than the front, but you are looking at 1-inch difference. This may be too tall.