You can get the grip level you require from 235/40R18 fronts and 275/35R18 rears "if" you purchase the proper tyres.
I have Kumho KU36 in those sizes, but you can also use Dunlop Direzza, or Yokohama Neova AD-series, or Bridgestone RE055, or Pirelli Corso Rosso.
If you go wider than 245 fronts, you will have trouble with the car following ruts in the road (we call it tram-lining here in OZ, I am sure its a term you'll be familiar with in the US).
I personally would not go as wide as 335 on the rear as this would require ~12-inch wide rim and I am sure that you;d struggle to fit the tyre under the rear guard on full bump.
You can see the amount of grip generated with my setup at
YouTube - BGTV8's Channel
The wider you go, the more you need a reduced overall diameter to ensure that the front tyre does not hit/rub on anything under the front guards (fenders) on full lock.
Many of the older 300ZX TT cars that went for ultra-wide 17 and 18" wheels on the front suffered engine failure because the tyre rubbed on the plastic shroud under the guard on the left front, and then wore away the radiator overflow bottle which then meant the radiator eventually lost enoigh water to cause an engine failure .... you need to understand the full range of issues before going ultra-wide on both front and rear as suspension and steering can be adversely affected if the wheels are not widened equally on the inside and the outside - this affects track (which affects relative grip front to back) as well as scrub-radius which can radically affect the "feel" to the steering and the response to steering inputs.
Do your research before putting your money down
RB