Im awake now

ET40 8j with a 215 tyre on the rear wth all your added bits ie diff mount,shocks etc will be fine . You should find the rear end dont squat .

When i fitted 17x8 revoloutions with 205's on my 3 door they lasted around 10 miles then i took them off as they just wreaked the arches .So really you have 3 options

1) trim the arches back and you may also have to trim the edge of the front bumper as mine also caught that, a pro would get it looking spot on ,or maybe you could fit another arch kit and keep yours safe ??

2)Have your front wheels machined to a different offset .

3)Remove the shims if there 20mm which would give you a little more room in the front arch

I spent hours on the phone to comp working out with them a nice size and looking wheel for the 3 door .These cars without cutting and messing about are hard to get a nice wheel on in 17/18 .Need anymore advice pm me your number and i will call you

Dave