I'm 6'2" and have riden 175s for years. As I recall, when I had bought a 58 cm road bike back in 1988, that's what came spec-ed on it.

A while back, I borrowed a bike from a friend while I was visiting in the DC area. It was a 58 cm and I didn't bother to look at the cranks. While grinding up a steep hill, I found that I HAD to shift at a certain point, I couldn't just grind it out; sort of like bogging a car. I thought to my self, "hey, does this think have shorter crank arms on it?" Sure enough, 172.5s. The longer crank arm will allow you to torque through a climb where you should infact shift, and most likely would. I don't know where I'm going with this other than to say try riding a bike with 172.5s and one with 175s and see if you can tell the difference or have a preference. I prefer longer but that suits me because of my height.