[grannyknot]

The car, an 08/Z4MC has on it right now style 359, 19x9/ET31 with 245/35 Pilot sport A/S3 on the fronts and 19x10/ET25 with 275/35 on the rear.
There is no rubbing and it's a good looking set up.
I will be spending a lot of time on the Hwy and the ride is a bit harsh on a rough road so was thinking about going with 18" wheels to gain that extra 1/2" of side wall. Do you think there will be a noticeable difference in the ride with extra 1/2" of rubber?

Also, I noticed the dia. of the front tires are 654mm and the dia. of the rears is 675mm, isn't that difference going to show up in some detrimental way?
I can't say I have noticed any problem with the difference if dia. but it just seemed to me the they should be the same ... or I could just be anal.
Thanks