If your offset is 0 to + 6 with your wheels, they SHOULD fit, clearing any suspension.

Guard rolling depends on total width and total offset - negative offset pushes the wheel out towards the guard.

A set of 20s with low profile tyres will have the same width and total height as a set of 17s.
I'm running 18x8s with 245/40 tyres all round. Kings superlows.
Clears suspension easily, doesnt scrub front or rear normal driving or loaded. My guards arent rolled either.
The right offset is key to fitting a big set of wheels, though I would recommend getting the front guards rolled regardless. If, for any reason the wheel does catch the guard (steep driveway, full lock perhaps), you will be fkn p****d off; I havent done mine as I havent found anyone I trust to do them and not crack paint yet.