Help with suspension/tire size combination...
 

Mods, please lock/delete.

245/40-18 is pretty tall for the rear. I think you should run 255/35-18 ideally or if you want 245/35-18

Remember that because you are differing from the stock diameter so much with those other sizes that not only is your odometer going to be slightly off, but you will have slightly different mechanical leverage putting power to the ground (like a final gear ratio).