Wheel size combo?

[SMF Speed&Custom]

I was wondering if anyone here can post some pics of some different size wheel combos here? I am debating on what size wheels to go with on my truck. I want to go with a lower profile tire like a 60 or 65 but also would like just a TAD bit bigger sidewall height in the rear tires than the front.
I was thinking at first 15 all the way around but with my truck not lowered yet and the truck (66) is so big that 15's dont look good with lower profile tires... too small in my eyes. So was thinking, how about 15 in front and 17 in back? Either that or 16 in front (to fill in the wheel wells more to give a lower look) and then 17 in back. Reason I want 17 in the rear is because I am running at about 3500-3650 RPMs on the freeway at 60-65 MPH so a taller wheel and tire I am hoping will help just a tad at least. Of course it isn't going to be a big difference like changing gears but no money for gears right now.

Thanks a lot for any help here guys!