i would say 176 im like 511 140 and thats what i ride. 176 sounds long but when they are mounted it feels so much shorter, but like nomensteven said if you're just starting out it might be a bit big, but if you're not defintely go 176
id say 170 if ur still learning 360's and shit, buttt if ur centering then get 180's. i would get the 180's and center them if u wana work on ur park skillz