According to the SAAQ (Société d'assurance automobile du Québec)

Here is the max. height for the JKU (not the JK)

Track: 157.23 cm
wheelbase: 294.7 cm

157.23 cm + 157.23 cm X 294.7 cm = 46335.68 /2 = 46335.68

46335.68 / 3104 = 14.93 cm ( 5 7/8" )

max. lift and body lift: 3 1/4"
max. tire: 2 5/8"
max. total height: 5 7/8"

 

This is the Law, but in reality, no problem with 4" lift kit. Samething with 37" tires. But they have to be inside the fenders.

BTW, are you in Quebec?