How to roll a fender lip?

You describe your 15x7s as having 4 1/4 offset. I assume you mean backspace.

Correct, I used the wrong term. I meant backspace.

If you change to a 15x8 with 4 1/2 backspace, then 3/4 of that extra inch is towards the fender, making your problem worse.

Help me understand why, because as I understand it, if the backspace increases 1/4", that puts everything closer to the springs which is what I need. The problem isn't the location or width of the wheel, it's the sidewall of the tire. The cross section on these tires is 10" which I measured and is correct. Does that cross section measurement change given a wider or skinnnier wheel?