you heard wrong. they measure the tip-to-tail length and that's their size- 179 is actually 179 cm long. some people say they measure the running edge length, but that's not accurate. measure them and you'll find out. every other ski company measures the same way- it's a "standard" much like the DIN system is a "standard".
call it standard, but k2's are longer than other brands. i work in a shop and stare at skis all day, and the 179 public enemy is the same length as the 181 teneighty. so there you go, they are a bit longer than other brands.