For me, I would use 8.0J with 235mm, 7.5" with 225mm, and 7.0" with 215mm. But it really depends on how it fits on your wheel. The tire shop should be able to tell you.
Z rated tires are for speed beyond 240km. It is just a general rating. Y is more specific (up to 300km)
And for FR, my guess that it stands for Front-Right. Is this a asymmetrical and unidirectional tire?