I searched and found nothing. I have a set of Qauntum Tek S13's from my previous car and they are 225 18's with a 42 offset. The stock offset for the tC is almost the same offset and tire size as my old sebring. Is that going to be flush with the fender in the tC?

Theres not enough info there to tell. You need to have a 5x100 bolt pattern first of all. Also what is the wheel width? That has a big impact on how far the wheel will stick out. If its a 7" wheel than it wont stick out much further than stock. If its an 8" wide wheel it will stick out about 15mm further.

It is an 8" wheel. Its one of the rims that have the 5x114.3 and the 5x100 as well. Heres a pic
http://memimage.cardomain.net/member_images/4/web/772000-772999/772394_14_full.jpg

Ok...then it will stick out 15mm further than stock which will fill in the wheel wells more..like adding a 15mm spacer to the stock wheels but it probably wont be flush