^My reaction to the 18x9.75 20p idea 😂
Having a little peek through the old files are we @A_J_T? Seems like your heading in a certain direction which both @ADIKT and I can assist with 😉 and you don't even own the car yet!
But in all seriousness, the larger/wider you go - the less room for tyre. I tried to keep the rolling diameter as close to factory as possible on my 8.5s which meant a 225/45 tyre, and that rubs on the inner guard liner at full lock (at my height that is).
Basically you need to cut the plastic flare that lips back inside (approx. 15-20mm), cut out the lower fixing point of the plastic flare and have all four corners rolled/hammered...
Will you be at the Westgate meet next @A_J_T? If so, you can have a better look at mine.