Anyone using 16" Split-spoke Mustang wheels on their car?

A lot is going to depend on the make and size of tire you use. A 235/60-15 (or -16) is going to present a 9.5" wide tire on a 7" wide rim using BFG T/As. The rolling diameter is going to be a little over 27 inches.

The 5.27" back space is a red flag to me. Mopar rims typically have a 4¼" to 4½" backspace. My concern is that the rims would put the tire into the rear springs. I tried 255/60-15 tires on cop car wheels on my Demon and the rear tires were almost on the stock located springs when sitting still and rubbing in anything other than a gentle corner.

In the front, there may be problems with the control rods, as well as the UBJ. FWIW I tried 255s on the front of the Demon and control rods rubbed on the outside wheel, the top of the fender rubbed on the inside. In fact, when I went to 235s, I still had to massage the fenders a little to get rub-free real world operation.