You'd stay close to stock spec.
TUV specifies clearance for snow chains on stock cars, thus the gap.
So it's possible then to tuck tbSTi Enkeis at 18x7.5 +55 with the stock tyre...
So that's max clearance. Eg most tuck possible.
Iirc 18x8.5 +45 with most 235/40 or 225/40 requires a slight rear roll up if slightly lowered.
That's your minimum clearance. Eg most flush.
I'm at 18x8.5 +35 235/40 with caster bushes front, camber f&r, lowered a little with a little poke.
Heaps of rolling, pumping and a little trimming.
Or right outside your comfort zone...
But I have Shockworks and a few reinforcements, so it all works superbly. And IMHO it looks awesome...
- Screen shot 2015-08-27 at 6.06.14 PM.jpg (75.92 KiB) Viewed 1862 times
So get on a rim and tyre calculator and extrapolate the rest. Eg somewher in between the max tuck and most flush extremes listed above.
But you'll get a better look by buying the rims with the offset you desire and rolling, trimming and pumping the guards to suit.
Tucking will reduce wheel travel ruining the ride...
Most importantly, what is your intent with the project?
Eg, my car, I wanted good load carrying and touring potential plus next level handling (Shockworks) plus a very rare and good looking set of rims with massive center crater which I came across on Import Monster. Luckily I like the pokey look, and we made them fit over time. It all just works but took a while to get right.
I would consider going even more extreme, eg a set of 3 piece rims with staggered/square fitment, eg low dish front to clear BBK and deep dish rear.
Now if I was to choose BBS LM for eg, then the front offset would go to +20 requiring well modded guards, flares or those DAMD fiberglass guards, S402 style.
In other words, megabux all round. Or a bit less with rare Simmons, Or a nice set of custom Koya concave monoblocs... Or Work Seeker... MmmmmMmmm