15" to 16"

Long story short... I have 2 Firestone Winterforce UV tires in 225/75R15...never used... I want to purchase 2 more tires this size, and a set of 15" steel rims to put on my daughters 2008 Element AWD which takes 215/70R16... I could get 4 - 16" steel rims for the Element then buy 4 new snow...