There is a nut on the front suspension mounts I think - this will probably need to be ground down - there is a pic on the forum somewhere.
I have stock rims, but went with the next size up sidewall ratio - on full lock my front tires sometimes rub the inner plastic fenderwell.
Rear tires are OK so far.
I have a slightly smoother ride due to a taller sidewall.
The offset spacing of the wheel will be your biggest problem, what's the offset on the new rims compared to the old rims?
You may have a bone-shaking ride with tires that have a sidewall like an elastic/rubber bands (or whatever they are called in this country).
Try and 'dry-fit' the wheel & tire combo to see if there are any obvious errors (like not fitting in the wheel arch/limitingsteering.