Originally Posted by US///M3
.5" decrease in overall diameter with no rubbing issues is better than the right diameter with tire rubbing, we're really talking about a .25" sidewall decrease in height.
For example,BMW recommends a staggered set-up, that doesnt mean a square set-up is worst...
I autocrossed on 255/35R19's, they almost rubbed through the wheel well liners, replaced them with with 255/30R19's (stiffer sidewall) with no issues, noise, still was the fastest car on street tires.
You almost make it sound like decreasing the sidewall height by. 25" will deteriorate thr car's handling.
The Worst option is a tire size that'll rub...
You are right I do think that running a 255/30 will deteriorate handling over a 255/35 tire (assuming the same tire). My opinion is that the sidewall on a 255/30 is small enough that it does begin to deteriorate both in comfort and performance. I acknowledge that the average driver may not notice it on casual street driving. I have had the benefit of being able to compare a number of wheel and tire combinations on the M3. I had 20" wheels with 255/30/20 tires on my first M3 (plus three sets of 18" wheels and two sets of 19" wheels). One of the reasons that I went away from 20" wheels was the the thin tires (less comfort and less compliance reduces grip). Plus a 255/35 will look far better because it will be more consistent with the rear tire and fill out the wheel arches. Why make that compromise on a 19" wheel when it's not necessary? Plus you lose the extra protection from potholes. When you say you almost rubbed through your liner do you mean the back side where it hit at full lock? If so I don't think that is worth worrying about...(again my opinion). If you rubbed somewhere other than full lock then I don't think your situation is the norm. If we were talking about 265/35/19's on the front of an M3 I would be right with you saying they will rub 99% of the time and it's not worth it (due to their large overall diameter).
You should do a search for 255/30/19 on this forum. You will find that you are one of the only people running that size (I couldn't find anyone else). There is a reason for that...
Another good source of info is this thread. Lots of data on 255/35/19's.