If I got 235/45/18 toyo t1rs will they fit my stock wheels?

 

yes. a bit oversized for the wheel, but not bad. they will also be a tad taller than oem tires which won't be an issue at stock ride height but may cause trouble if you go with any sort of super low or maybe even some semi-aggressive drop like the tein springs

 

235s seem awfully large for stock wheels, especially with such a low profile. Quite a bulge would that be...

 

+1

225/40-18 would be a bit big for a 7" wide

 

yeah, but it can be done, though the turning performance aspect of the wider tire would be lost due to the fitment and inevitable sidewall flex/tire rolling over onto itself. i've seen mustangs and camaros running 295s on 9" wheels, great for drag use but wont turn well at all.