Stock 215/45/17 and 245/40/17 or typical track-trim 225/45/17 and 255/40/17 have diameter around 24.6" - 25".

If I run the front with 225/40/17 (23.8" diameter) and keeping the back at 245/40/17 (24.6" diameter).
Will the 1" lower front diameter have negative impact to ABS brake proportioning or any negative impact to front handling (bad roll center change?)?

Thanks

 

It may screw with the VSA (and possibly the ABS since the systems are related). There have been a few posts on here that front/rear tires that are too different from each other will confuse the system and disable VSA/ABS.

However I can't tell you if 1 inch diameter difference is enough to affect it.

 

you will be fine. i have run 275/40-17 all around, 255/40-17 all around, 245/40-17 all around, 245/40-17 front w/ 275/40-17 rear, 275/40-17 front 295/35-17 rear with no abs/vsa issues.

edit: bolded certain items for the blind.

 

275/40/17 all around, 255/4017 all around, 245/40/17 all around means the front and rear are spinning at close rate AND they are close to OEM ride height/diameter.

275/40/17 front (25.5") and 295/35/17 rear (25.1") means front and rear are still within less than 0.5" diameter difference.

I have no experience with 1" diameter difference between front and rear ; don't know whether 1" smaller front will have any negative impact to suspension geometry.

 

a shorter tire will have less grip than a taller tire assuming the width is the same.

 

umm, guess someone is not good at math. lol.

245/40-17= 24.716

275/40-17= 25.66

so, .944, just shy of an inch. no problem.