It will depend on your rim IW. Again, I had a buddy run 42’s, F & R, on his Crux for The Rift with no issues (but very tight). But his wheels were probably 19mm IW since they were from 2016/17.
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What year is your crux?
I run 47 Pathfinder front and rear with room to spare. But my bike is a 2022… I think OP was 2020(?)
OP ? 
Its a 2018…
But does it make sense to have different sizes on front and rear, as there is A LOT of room in the front
OP = Original post. The first poster had a 2020 bike.
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I think that is a personal preference. It seems a lot of the top pros are starting to do that as their frames are limiting their tire size more than their forks. Unbound saw several running MTB tires up front and 45-48 tires in the rear.