15" rims will fit on a JK, but you need to do it right.
I'm running 35's on a 15" rim. it's 50/50 if the rims you've picked out will fit. our brake calipers are HUGE and they rub the rim. now, most folks take a grinder to the calipers and shave off 1/16" to correct the rubbing...
but I discovered an alternative through trial and error when picking out my rims. the suggested backspace for a 12.5" wide tire is 4.5. it's too much. 4" is too much. I have NEVER seen a rim though with 3.75" BS rub the calipers, including mine
downside to this is your tires stick out about 2"
if you like that look, fantastic. check your laws though as this is illegal in some states.