255/45/18?
 

Anybody switch up their 7th gen to this size. One website showed it was ok. Just wondering about width clearance. Would like the wider tire.Go from 235/50/18 to that size. Thanks

im really not sure how this works but it may help. its a fitment guide
Custom rims, wheel tire packages for your ride - RIMSnTIRES.com

you shouldn't have problem with clearance i believe thats what the factory grand prix gxp came with. btw that's what i ran on my old 6th gen and mine was lowered.

Thanks guys, that website says they are just fine.

np i kinda answered that question for myself too lol. i just thought 235s were the widest

I have done this, with 18x9 Rims and a 34 offset
I would suggest though, or something to keep in mind, and i will be posting a thread about it.
Anyways, the inner lip on the rear fender well is just bent in at a 90 degree angle, which isn't much of a problem normally, however I noticed a problem after I hit a speed bump that I didnt see coming because was in an unfamilar part of town. Cussed as i did and apologized to my car lol.
Long story short, in this type of situation, with severe wheel travel, this lip can be a problem with cutting into the outside sidewall of the tire. I have my winter (stock) wheels and tires on now, but plan to get that lip rolled up by a body shop before spring.