What are some good sticky street tires with the ZR speed rating?
I am currently runnimg 245/40ZR18 tires all around but want some 275's in the back. Have 18x9.5 C6 Z06 wheels all around.
What size is closer to what I have. 275/35/18 or 275/40/18?
What are good sticky street tires in this size also?
I don't want so sticky that when I dump the clutch that I'm gonna blow my diff apart (4th gen diff). I would still perfer my tires to be my weakest point, but I still want good traction.

 

Get a set of 275-35-18 sized tires for all 4 wheels, they are the correct height and will work right.

Nitto NT05 or Falken 615K would be good choices, just don't expect good rain performance from either.

 

I'm not worried about anything other than dry performance. The car is just an expensive toy that doesn't see anything but sunny days.
Are the 275's actually gonna bubble out on the sidewalks (tires wider than rims) or are they about the same width as my rims (9.5" wide) ?
I'm not sure how much room I have in the front

 

9.5" will fit a 275 width tire just fine. Both tires mentioned above have the "rim protector" band, which extends beyond the wheel lip to protect against minor curb scrapes and honestly looks better. Forgot to menion the new BFG Rival tires too - test results are very good. Don't have any experience with them as they aren't available in 275-40-17 yet.