If you are using the stock charger that came with the vehicle- it presents a 32A load
So a 30 A breaker will not work (as it will trip at 24 A - due to the 80% safety rating factor)
but a 40 A breaker will work just fine (40*.8=32) - if you can find one, actually two as it is a 240V circuit - 4 wire: 2 hots from different legs
I have been running mine w/ a 50 a breaker - and so far - no problems
Note: NEMA rating on Plug/Receptacle is a 'not to exceed' rating so giving the 14-50R a 40 A circuit is OK.
Lastly - to akirby - yes, and No -
you can get slim profile breakers - but you will need a 4 pack with the two 40 / 50 A breakers tied together
THis will consume two spots - but that is what is needed so that you get the 240 VAC and tap into each hot leg of the distribution panel.