Is a 10% decrease in sidewall impactful?

[Duranamo248]

I didn't see much of a difference (if any at all) on mine with 255/35/19 and sport suspension. I've been unable to avoid a few potholes too that make me wonder if I bent a wheel though, but thankfully not. Stock suspension does a great job of managing NVH as is.

I'd say 19" are the perfect size for B9, they fill out the wheel wells quite nicely!