12.5 Chubby worked for me, but I had to extend the lines.

 

16" apes on an 07 Road King. Much more comfortable than stock for me. I'm 6'4" though. IMO, if you are going to clean up the bars with apes, you may as well spend the money and do the cables in braided lines and run what you can internally. I did thatand am extremely happy with the clean look. Just my opinion. Good luck with your choices!

 

I am looking to install 16' apes on my RK and was wondering if that would be the right size. Im 6'4 and also was wondering if I would need to replace the cables and lines. Thank you

 

I did the 10.5" Wild 1 mini apes on my 2007 RK Custom. I'm 6' tall with a 32" inseam. I ride a Mustang touring seat. The bars come just below shoulder height, giving me the "badass biker" posture that I like when riding. Super comfy. I sat on a few bikes, measured their bars, even sat on BOTH the Heritage ST and the new RK with the Heritage bars (those are NOT the same bars, by the way). Measured those. Liked the Heritage bars on the RK but wanted just a bit higher and a little further apart. The Wild 1 WO515's were perfect. I did not have to lengthen any cables. I did have to move the throttle and idle cables around in the nacelle, but never had to take them apart. I did bend the front brake line - but only a bit. Key point: even if your cables fit, you WILL need to get them adjusted (or do it yourself). I needed a little help with that part, but got it done for under $100 for the 3 cables total. Here's a pic of the finished product:

 

5' 6" 16" apes 07 Roadking. Mine do curve down to 14" though, should have hade them years ago. Hade them installed new cables and brake line for $800.