Quote Originally Posted by edwardb View Post
The Factory Five parts catalog (https://www.factoryfiveparts.com/) gives dimensions of their wheels including backspace. That's where I'd start for reference. The 2015+ IRS setup works fine with those dimensions. No matter what ratio you choose, the track width is the same for all. The Wilwood upgrade brakes fit the Factory Five 17 and 18 inch wheels. You'd need to check any aftermarket wheels, but not sure quite how you'd do that. 15's are a non-starter for that package. Although I've heard Factory Five now has a 15" option for Wilwoods.
Thanks edwardb - That is exactly what I was looking for!

Front Wheel Size (Diameter x width): 18"x 9"
Rear Wheel Size (Diameter x width): 18"x 11"
Front Wheel Backspace: 6.00" (24mm Offset)
Rear Wheel Backspace: 6.46" (12mm Offset)
Wheel Lug Pattern: Ford style 5 lug x 4.5" bolt circle
Color: Black
Front: 255/35 ZR18
Rear: 315/30 ZR18