There's a laundry list of issues that you effect when you change a tyre and wheel setup on a car...
In the case of the FRP, the original chassis is just not designed with 'Big' wheels in mind hence the lovely tickford mod at the front underneather the carpets..lol also the rack and steering is not really designed for it either, the turning circle on the 17's is bad enough as is! then there's the not so obvious changes of ride height, change of shape of the actual contact patch on the floor.... plus your going to have to bin the front carpets which not only deflect a lot of muck and water, but also make a big difference acoustically speaking....
then you get onto the finer issues of tyre choice in that size, which will probably have to go down to 35 profile...mm, comfortable NOT..
Plus, 'Premium' rubber that will complement the car in that size will be very costly, which probably means you'll end up buying budget tyres, which will make the 35 profile seem even worse
...
Still like the wheels... ??