You got me thinking. You have to take into account that they are a twin tip ski.
In your case at 5'6" that would make you 167.6 cm's tall. That would make your skis 8.4 cm's taller than you yet you say they are only a mm or two over your head. It's all in the tips.
Here is the link that converts inches to centimeters:
http://www.manuelsweb.com/in_cm.htm