20" rim offset backspacing

Hi first off i'm new to this group and I have a question about some rims and tires.
Here goes.....I have a 2003 ford explorer eddie bauer with the 17 in stock rims at stock height. I was looking on getting 20 inch rims with 275-45-20 tires. I don't want the tires and rims to stick out past the fenders. The question is does anybody know what offset and backspacing is best? any info on this would be a great help.

 

[bmxking5]

Draft (on this site) has some tires/wheels that are just the size you're talking about. Personally I think that his are perfect. http://www.cardomain.com/memberpage/510194/3 I don't know the backspacing but you can send him a Private Message and find out.

 

[vegastrac]

I have a 5mm offset with mine on my sport trac. Although the trac is a little narrower than the regular explorers, I think this is the general range you should be looking at (5-20mm) As you can see from this photo, the rear wheels are recessed some. I plan to add 1.5" wheel spacers in the rear to even them out.

I do have slight rubbing that I recently detected in the front drivers side at full turn on the sway bar. I plan to install 3/8"-1/2" spacers up front to see if that solves the issue.