sad to say but looks like the tyre comparison you mentioned does not care the car is RWD. or you took AWD?Not sure what I'm missing. As shown by
Tire size comparison the easy way. Use our tire size comparison calculator to compare diameter, width, sidewall, circumference and revolutions per mile.tiresize.com
235/55/19 is very similar to 255/50/19.
suggesting that the 235/55/19 'square' setup is reasonable.