WINTER TIRES QUESTION

hey i have a 2010 lancer gts and im looking for a set of winter tires on steelies. right now i can only buy them from canadian tire because i can get 15% off and they're the only company i know that provides a finance payment option. im trying not to spend to much but im trying to get good winter tires at a decent price. i have tried the tire selecter on the canadiantire website and its telling me the standard size for my car is 215/45R18 89 W and most of those tires in that size are expensive . im wondering if i can go smaller so it can be a bit cheaper?
can anyone help me select good winter tires from the canadian tire website ?

i got some good hook ups on winter tires and steelies. I can't offer the financing option, but it will be cheaper than what you find elsewhere. shoot me a pm if you are interested.