255 is 10", 55 is 5.5"
275 is 11", 55 is 6"
Not that short, especially compared to modern truck options.
6" sounds alright when you put it like that.
Looked at a few different trucks and they all had 70's in that range. It just "looks right". Good amount of cushion for doing truck stuff.
Some visual trickery at play as its only an inch or so different than yours and looks better on 16's than 18's.