I put about 800lbs in my trunk and the rear end dropped about a quarter of an inch. I think you'd have to hit something pretty hard for it to sheer something. 20x11 PK Auto replicas 315/35 Nitto NT05s.

 

^^^ I have 305 Conti’s on 11” wheels with to issues. Car is lowered a fuzz over an inch too. My offset must be in tighter. Not sure what mine is. Velgen just sent these knowing what car I have.

I’ve since had a suspension kit installed to dial in the camber but still didn’t poke the tires out much more than in these pics.

 

If you need the offset I can find it, but it's whatever PK auto BIG brain guys figured out. I never had any rubbing either. I ran Nitto NT05s 315, NT05Rs 315, and 555s 315 with no issues but I did get a few people asking if I was worried about a bad pothole (we have potholes here that require spelunking gear to retrieve unwary joggers who fall in) that it would shred a tire. Also, because at full compression, due to camber, I don't know if they would even touch.

 

If you need the offset I can find it, but it's whatever PK auto BIG brain guys figured out.

That's not too difficult to figure out: I have a bunch of cheap crappy spacers that I can play around with to see how the tire sits. 21 mm seems to be the limit without the risk of rubbing at 3 o'clock against the metal parts. If I take a sledge hummer to those pesky ribs at 3 o'clock, I could probably get away with 23-24 mm offset, but even in this case the tire will stick out a bit.

Also, because at full compression, due to camber, I don't know if they would even touch.

I raised the back of the car on both sides (that's the only way to do it with these cars IMO), put a cinder block under one of the rear tires, and lowered it. The opposite rear tire was handing in the air, but I didn't get the full compression. The top of the tire ended up a bit over 3/4" from the edge of the fender, and it was obvious the it won't clear it even with camber (at least on my car: different cars may have different camber).

 

I ran a 18mm offset 11in rear wheel with a 305/35 R888R all last year on several road courses, bouncing over berms with no issue. The car is lowered with MP springs.
This year I'm going to try 315/30 Toyo RR tires.