I could have sworn I've seen e82s run big slicks but can't seem to find evidence to support that.
This was the only thing I could find and it didn't have that meaty sidewall -- 275/40 which is what you've already done.
https://www.1addicts.com/forums/show...&postcount=327
Having seen what 26" does to the rake of e92s, you're definitely going to need to raise the rear regardless.
I believe the softness and height of the oe springs will be beneficial for the actual squat.