Surely you mean +40? -40 would stick out 3.4" further than these do...
18x9 +30 with 235/40's
I've only lipped the guards thus far, but these tests showed that the only place the tire contacted the car was the outer lip of the guard - even at full lock and max suspension compression the tire still clears everything else (I removed the outer guard panel for full lock tests, no pics though).
I should point out that if you have stock steering tie rods they will hit the chassis long before you get this much compression (about 35mm ago)
This offset calculator is incredibly helpful
link
using this it's quite easy to make a cardboard mock up of your wheel so you can check how far in/out it will sit - remove the spring and jack the suspension through it's full range of motion.