Hello! I don't own a birdy ... Yet . I plan to buy one (Alfine disc) in the near future.. And I have one question to you all: is it easy to put 20" tires and wheels on a recent/new birdy ? And can I put all sorts of 20" or is there a max.width due to the wheel/front fork clearance?

(After a lot of searches here and g..gle, I understand that older birdies require some hardware changes but I can't find any info concerning the actual models)
THANKS!