Wow, thanks all!!
Ok, so I agree 275/35/18 looks entirely reasonable on the front even if I did decide to use this setup on the road. I'm still a tad worried that the slimmer-than-OEM 265/35/18s in the rear might look strange especially on stock rear suspension, but I'd only go 265s all around if I wanted to use tire models for which 275s weren't available, like the AD08s (though I hear they run wide) or the Pilot Sport Cups. I guess I'd just have to deal with that in that case.
OC3, why did you move to a 10.5" wheel while sticking to the same 275/35/18 setup? Was a 10" not cutting it for you, or was that just to enable future (literal) expansion? I'm surprised you had rubbing on full lock since I was advised that wasn't an issue, but good to know it's not an issue most of the time -- and you're running a lot of negative camber. I'd probably be running AD08s or NT01s on mine fwiw.
And lastly, I'm hoping to hang onto the stock suspension as much as possible (except the camber plates) -- trying to avoid going ALL the way down the mod slippery slope as much as possible (though I'm already accepting that I'll probably want a BBK especially if I start running R-Comps). But just out of curiosity, how much have your suspension changes other than front camber improved track handling, and what percentage of the improvements you saw from suspension + tire changes do you think I'd get just adding camber plates and a squared setup with larger rubber?
Thanks again for replying so quickly all, this is why I love this forum!