2011 4x4 sport 15's rub calipers..
 

Pretty obvious question, but is there no way 15's fit the 2011 4x4 sport? I thought all 15's fit the rangers. That's why most get them.

they should i believe there the same unless they won't clear the rear calipers on the 10s and 11s

What wheels are you trying to install?

It really depends on the wheel. Backspacing plays a big role on 15s fitting the 04+

this is probably the problem^^^

x3. I have 15's on my 04 that already has the larger brakes with zero issues. I doubt the rear disc set up on the 2011 should give you a problem with the appropriate backspacing specs.