hmm, that tire size is bigger in diameter than stock. stockers are 215/45/18 with a 25.7" diameter. For winter I'm running 205/60/16 which has about the same diameter. The tires you have are around 26.9" (this will vary a bit depending on rim width and tire model). That could cause rubbing, which could cause your steering madness but I'm not sure. The factory diameter fills the wells pretty good, I don't know how much extra room there is for taller tires.