yo tim... so far in the rear, where i currently have my rubbing issues, going lower should make more problems with rubbing on the fender. the suspension articulation makes it look like the wheel moves out as it compresses, which will give me more room between the tire and strut. ill definitly have to look into rolling (maybe even pulling) when i do a suspension.
for the front, i have 18x9. i was looking for a tire that slightly square or a barely pulled on the sidewalls. i definitly dont want bulge on the front. the 255/35 Bridgestone S-03's i have up front appear to be pulled/stretched so thats why i was thinking about going a hair wider. plus, the sidewall is so short compared to the rear, going the additional width could help fill the fender a little better. with the tire on there now, there is quite a substantial fender gap and it makes it look like i have to bring the car down 2 whole inches.
ideally, id like to get the top of my fender opening to sit ON the top of the tires, visually... or perhaps a one-finger gap.
id think that you could get 275's up front with the right sidewall height and ride height. those 265/30/19's fit pretty well and the car was lowered. the tires even looked stretched on those wheels so i think a 275/30 would still fit on the same setup. but again, im unsure of how well itd interface when turning and going over bumps. i have a feeling that theres a good chance the tire could grab the fender on hard turns like driveways if i didnt take them slow enough. i had that problem on my RX7 and sean/2jzmk3 does too w/ his advans.
the 315 in the rear, im quite convinced there will need to be some pulling or going back to stock ride height. the 305/25/19 i put on the rear of my old car, was +50 and hit the strut at full droop. i had to put 10mm spacers to push it out and the tire STILL touched the strut. only after i put the car on the ground did the tire gain space... even then it was only a few mm tops. so basically, with the tire nearly Touching the strut and a 19x11 with a 305/25, it BARELY protruded past the body line. if i was able to run that w/o rubbing inside, i would have to do some fender rolling and a slight pull or mess with the camber.