I would not get them in 19's. Reason being because the tires for 19's are supposedly harder to find and more expensive seeing as how 18 and 20 is a much more common size that pretty much any real auto customizing shop will have.
Also I could be wrong but I thought not all Mustang wheels were compatible on Explorers? But anyway those wheels look very sleek.
I understand that the prices would obviously be higher for bigger rims, but the main reason i would do it is because you dont see many people rolling around on 19's .. But again, this is just my opinion!