That size should be fine:
https://jeepgarage.org/f109/275-55-2...ims-91174.html
Plenty of good info in here:
https://jeepgarage.org/f190/20-tyre-thread-50571.html
275/55R20 are a popular size, BFG KO2 are popular in 275/65R18 size and they are slightly bigger than the 275/55R20. I have STMaxx on 18s they are a little bigger again, running out of room with the control arm going any bigger than 32 inches.