Originally Posted by slicer
Thank you for adding specifications to the conversation. I think that is a big help. I added a couple more in red for comparison (all Michelin PSS specs). I should clarify that according to BMW the only "right" size for the front is 245/35/19. As you can see above, if you want to use a size that differs from stock, the three sizes that the are closest in overall diameter to OEM are 255/35/19, 275/30/19 and 275/35/18. The 255/30/19 is the furthest away from the stock diameter (AKA worst option IMO). I don't think my post was "miss-leading" in any way. I specifically stated that some people will have rubbing at full lock with 255/35/19's depending on the tire brand, wheel offset, and specific car tolerances. I should add it is also dependent upon wheel widths (which will impact the stretch of the tire) and alignment specs. I personally have used all three of the above sizes plus 255/30/20 on two different M3's (my recommendation was not based on a google search). I have had slight rub at full lock 50% of the time with 255/35/19's. My current front wheels are 18 x 9.5 et22 with 275/35/18 and I have no rubbing. I did rub at full lock on with the same wheels / tires on my previous M3. I personally don't think a slight rub at full lock is a large issue (and is worth the small annoyance to go to a wider tire). I also know there are literally 20-50 threads on this same topic plus 100's of posts....And many people who have successfully ran 255/35/19's without rubbing. The tolerances are tight on the front of the M3 which creates this issue. At the end of the day, I would not consider putting a 255/30/19 on the front of an M3 because the sidewall height is shorter than necessary which is a big compromise. You would be better off with the stock size (245/35/19).
.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...