With a 15x7 and a 4.25" backspace a 225/60/15 is pretty much all the way out at the fender on a BBP car, those are +6 offset rims. A 15x6.5" with 3.75" puts that tire a 1/4" further out toward the fender, that's a 0 offset rim. I wouldn't say a 225/60/15 can't work on that rim, but I know on my Duster when I was running 225/60/15's on 15x7's with 4.25" backspace I didn't have a 1/4" to the fender to spare. That 15x6.5" would put a 225 out further than the 275's I run now, and my fenders are rolled to run the ride height I'm at with those.
If that's really the backspace on those rims, I wouldn't go more than a 215 up front.
