Stock factory offset for the BBP disk brake wheels was +6. That’s a 15x7 with a 4.25” backspace (cop wheels) or a 15x6 with a 3.75” backspace.
With a 15x7 and 4.25” of backspace you can run up to about a 225/60/15 without permanent modifications. With a Barracuda the wheel opening is a little limiting, the front lower corner of the fender gets in the way if you go too tall with the tires. You definitely want to stay under 26” tall unless you’re running really skinny tires.
But with 15’s I’d stay with 15x7’s and nothing bigger than a 225/60/15 unless you want to modify stuff.
