Was thinking about running 235/45/17 on fronts and 255-40-17 on rears or something of that nature. Would there be a difference in steering response than 255 all around

 

I would do 235/40 up front instead. Bias the opposite direction. 235/45 is a taller tire then the 255/40 and that additional sidewall will flex more creating a less desirable steering feel. The other option if you want to get even closer would be to run a 245/40 up front if you think you can make it fit. But these are the only two tire options I would consider for the front if you dont run a 255 all around.

 

Thanks. I'll see what pairs match best on outside diameter

 

235/45 are a little closer to the diameter of a 255/40, but I would still go with 235/40-17 fronts and err on the side of smaller front tires for a number of reasons:
smaller front tires biases braking more to the front => more stable
smaller diameter fronts will be an easier fit, much less likely to rub even at the same width
smaller diameter fronts than rears looks infinitely better than smaller diameter rears than fronts
slightly more rake with 235/40 vs. slightly less with 235/45 fronts
shorter front sidewall => more responsive steering
235/40-17 is a better fit on 17x9" wheels than 235/45-17

 

I agree, 235/40 or 245/40 up front. But to answer your question, yes you will feel a difference in steering response (e.g. increased oversteer).

 

A wider tire with a taller sidewall will definitely feel more vague on the road. Your better to compromise that in the rear if you have to, but not up front where your steer, preferably.

 

If you're decreasing grip up front in proportion to rear, wouldn't that be backwards?

 

Sorry, I meant you'd get increased oversteer running 255 all around. But yes you're correct, decreasing grip up front will increase understeer.

 

i like the 235-40-17 idea. now a 265-35-17 in the rear might work pretty ggod too

 

Why not go with 255s all around? A thick front sway bar will keep the car balanced. If you have square wheel sizes you may as well do it. It's what all the STR guys run