Have done some tests on this and found:
VTA car 17.5 Blinky pulled 35-40 Amps on dead start (burst) average 7 Amps down a straight
4wd Buggy 17.5 pulled 35 Amps on dead start, averaged 12 amps on a straight
So based on that a 35A Esc is plenty (as burst rating will be 100ish)
The ESC can't provide more than the motor wants, the lower the motor turn the more amps it will pull (at least with 2 pole motors)