I had 20's on my 03 maxima for awhile. The first set I got rubbed on the tire well and popped a rear tire when I had people in the back. Just got to make sure your tires are wide enough (maybe go for a 275 vs. 235) and make sure your offset is correct. the second set of 20's I got were amazing, they make my Maximus look so aggressive.

 

get ready to buy struts and control arms!!
im still suffering from when i had my 20" chrome
never again!!

 

I had 20's on my 5.5 at 1 point. Looked ok, but rode absolutely terrible. Switched to 17's and will never go back. I now have a nice smooth ride, better performance, and better gas mileage.