Depends on the years of the wheels...
I have run both 16" and 17" Mustang GT wheels on my 99 Explorer Sport and I had no issues as long as I used wheels that were made before 2005 MY... Ford flattened the Mustang wheel that year and that decreased the backspacing moving it closer to the suspension on the Explorer. I have test fit a set of 2008 Bullits on my truck and I didn't think they were too close to anything but I decided not to run them since they were 18"s and to keep the rolling diameter the same as stock I didn't want to run the tires i found...And I have not ever run spacres on this truck; I just don't care for them... Just my personal experience...
For the 16"s I run a 235/70-16; for the 17"s I ran a 235/65R17...These sizes kept the speedo readings close to exact and I didn't have to reprogram the PCM just to deal with tire size difference...
But, of course, YMMV!!!