you need to be running 17's and you'll also need to make sure the offset is great enough

if you want measurements i'll sor thtem out later today when i get back from ff but i tried to fit them to the mondeo and both the disc and the calipers needed another inch worth of offset before they would bolt up

can't remember what the mondeo (mk3) offset is on the 18's but that shoudl give you some idea as to how much you'll need