I'm 6'3", so only and inch taller, inseam is 34.5 inches and my go to frame size is a 61cm, at least with the classic horizontal top tube geometry. That gives me plenty of adjustment room and is not the largest size frame I can ride comfortably but rather the best overall fit. I used to ride a 58cm but I eventually realized that was too small and short. I needed to have the seatpost too high and the bars were too low, uncomfortable for long rides. My brother is 5'10", also has average length legs and rides a 56cm while being able to fit up to a 58cm. I think his inseam is around 32-ish inches. I recently built up a 58cm frame (with horizontal top tube) for a friend who is 6 foot with a 32.5 inch inseam and that bike fits him quite well. Another friend rides a 58cm (again with horizontal top tube) who is 6'2" but he has slightly shorter legs than me and is young and can handle being leaned over more on the bars than I can and rather likes the aggressive position.
Sorry but I don't have any of the top tube measurements handy or memorized, just the seat tube measurements and all of those are as measured from center to top.
Hopefully those data points can help you in understanding how well you might fit a 55cm.