I don't think you're likely to be able to go any bigger than 9.5 without at least pulling rear fenders.

 

it is not as simple as just how wide of wheel but offset, spoke face design, ride height and of course tire size. Manufacturer also matters since every designs the faces of their wheels different and this plays a role on caliper clearance.. TEs you can actually go to a 10.5 and as long as you stay above +18 you wont need to "cut" anything. Also by "cutting" do you mean rolling? Most folks do not cut their fender as rolling them flat achieves the same purpose. Cutting will only save you a few millimeters. Also the next logical step beyond a roll is a fender pull which usually done to the rears. I recommend you find someone that knows what they are doing or risk buckling and even paint cracking.
With CCWs you need to talk to them and see what offsets they recommend for the X... I assume it is a X you have based on your profile pic. Look in the Ultimate Aggressive Wheel thread Evo X version.

Good luck.
I have even seen folks running 18x11s by adding a pull to the fender.

Also if you do own a X you are in the wrong section.

 

Rolled or cut?

You can fit 18x10.5's with 20 to 25 offset and 275/35's with just rolled rear fenders.

 

Thanks for the replies. I am having the fenders rolled. I just don't want to pull them or cut and add flares because I like the natural body lines. I run a +22 offset with my TEs now and that seems to be the consensus on best offset especially for those wheels. I am looking to stay with TEs or have something done by CCW that is similar, so the spoke design/face etc would be fine for caliper clearance.
My ride height is very adjustable since I am on Fortune 510s, I just like a lower setup since it handles better in autoX in my experience. It's good to know that rolling them will afford me that much more room for wheel/tire. A 275 would be as much as I would need anyway, so that's great news!

Sorry if this was the wrong section, it's titled Evo X Tires, Wheels, Brakes & Suspension, so I assumed since I do have a X and this was a wheel/tire question that it was the right spot? But either way, you guys have been helpful

 

I assume the thread was moved by a mod, because I first saw your thread in my subscribed sub-forums and I'm not subscribed to any Evo X subs.

 

Won't camber have a pretty big effect on what will/won't fit?

 

Depends on your definition of "pretty big", but yes, it does have an effect.

 

What is the conclusion of the size here? I have similar set up running 18x9.5 ZE40s with 265/35 Hankook V12. Is it possible to go 275?

 

Yeah 275 are possible but I doubt you will do it without guard rub. Unfortuantely beyond 265's that means rolling guards etc.,