I have no fender or wheel well mods but I am dropped a little on coilovers. As far as street tires on stock wheels, I've had quite a few sets of 245/40's on front and 275/40's on back, and even though I'm lowered about 1-1/4" I never had a clearance problem of any kind. IMO if you put a 275 on back you "need" more than a 235 on front to reduce understeer.
With R compound track tires which have much stiffer sidewalls and can take the "abusive fitment" I now have 255/40 Toyo RA-1's on the stock front wheel and till no clearance problem even with very hard cornering on the track; other serious track guys here have used 255 Victoracers on stock front wheels, but that is also a very stiff sidewall track tire. I don't recommend a 255 street tire on the stock front wheel since the tire is too wide for the wheel imo, so I say go with 245.
correct, a few people have and are still running 315's on the stock rear wheels ...not a good fitment imo and since the tire is so squeezed you don't get an improved contact patch compared to the 275. Some people like how it looks with the 315's.