I'm from the old school and I recommend 17 because the tires and with street drawing in 19 all or almost all are for off-street. And my recommendation is 2.75 up front and 3.00 back. This English is with a translator.
The version of 120 volts withstand 125 volts is because it is easier to set 30s lipos than 29s lipos because the 5s are difficult to get in some brands.
To vent a hub engine is not making holes and nothing is the way or rather the angle look at this.
https://sites.google.com/site/shelbyelectro/motors/mods/ventilating-a-hub-motor
Not much English but try to explain.
my case.
48v-15ah (48x15=720) changes to 72v 10ah (72x10=720) so I stay the same autonomy but with more torque and speed.
your case
36v10ah (36x10=360) changes to 72v5ah (72x5=360) some autonomy more power and Speed.
(Google Tranlator) Sorry edit because I'm...