I appreciate the link but in my opinion their specs are extremely light for wire gauge in some examples. I'd never run a 30 amp circuit through an 18 ga conductor, much less 50 amps through 16 ga as suggested there!
I never run anything less than 14 ga anywhere in vehicle/bike wiring. Also vehicle specific wire is different than residential or commercial/industrial wire, being more strands of finer gauge conductors.
Please note the instructions above the graph, to include the full length of the ground/return to chassis ground in your length calculation. A 5' current-carrying conductor could have a 5' ground return, so you'd need to calculate for 10' length, not the 5' length!
Also want to be real careful about sticking in a short piece of light gauge wire in a circuit that's primarily heavier gauge, as the lightweight piece can cook like a fuse element because the larger wire it's patched into has higher ampacity. Similar to patching a 1' long section of 1/2" garden hose into a 100' run of 2" high-pressure fire hose, not altogether good.