[Patrick]

What numbers did you use in the calculator?
Your diff ratio is 45/11 = 4.0909090909'
It's hard to tell exactly what pinion you'll need to get those sorts of speed, because things like tire ballooning, voltage drop, and motor loading can vary a lot, but on 4s I'd say 20-22t pinion, and 18 or 19 on 5s.