Forgestar CF5 - S197 Fitment
Race Ready Motorsport is no stranger at fitting wide wheels under stock fenders, including the S197 Mustang. Depending on your goals RRM can get you set up with wheels that fit right.
The 18x10 will fit with no suspension mods on all four corners, with an added benefit of having the wheels be rotatable front to rear. You can comfortably run tires from 275 to 295 wide on all corners.
The 18x11 will fit with very minimal suspension mods and do have different offsets front to rear. You will need a way to adjust camber up front (Camber Plate), and have an adjustable Pan Hard Bar out back (or a Watts Link). With the 18x11 you can run tires from 295 to 315 on all corners.
Wheel prices are listed as RAW (no finish) which helps cut production time to around 2 weeks. If you select a standard or custom color the lead time can extend to 5-8 weeks.