18's on an A Spec????

hey all...great forum, lots of info!

I have a 2014 TL A Spec that I bought this spring, my third TL and I love it.

Looking to put some winter tires on for our wonderful Alberta winters and I'm curious if any of you know of any limitations to putting 18" wheels on it? I've heard some rumblings about the A Spec having different brake calipers or something so 18's arent' advisable....

any thoughts?