This wire isn't teflon, but it's still a fun example of too much current for 4awg cable.
It's also important to realize that your controllers output (brushed or brushless alike) can be outputting 100-600amps (or whatever) to the motor while your battery current may be only 30-40amps (going slowly up a hill in traffic or whatever), and you don't even realize how much burden your motor cabling is under.