Yowzilla
50cc
92" Edge (and all 3dhs 50/60cc) is 5mm diameter axles, but those like nice for a slightly smaller airframe
Are they 3/16" or exactly 5mm? I found some Titanium ones that are 3/16". Look a bit pricy..
http://whiteroseeng.com/products/Maingearwheels.html
The drawing showed diameter of 0.19" or 4.826 mm...