I ran those exact tires on my leveled 05 on the stock chrome 20's with no issues or rubbing at all. I do believe the 4th Gen's have less clearance between the back of the tire and the upper A-arm though. I ran with a 2" wheel spacer and without any spacer at all. Just to be on the safe side you could just run the 1/4" spacer to be sure you have no rubbing at all.
Let me see if I can find some pics of my 05 with those tires on it.
Edit: here are some pics with and with out the spacers