I'll bet they don't exist and likely not in 18" either.
I had no luck finding any 17" or 18" when I was looking in 2010 for my 2011 ... cheapest wheels I could find were 17" aftermarket "MB" brand from Discount Tire Direct.
You don't really need to go with 19" for your winter pkg. since you don't have PP ... I would think an 18" package (both wheels & tires) would be less $$.
You don't need 235 wide tires either, as the 225/55-18 will mount on up to an 18" wide rim and is 1/2" Taller (27.74 vs. 27.25" for 235/50-18).
On Tire rack ...
255/40-19 Snow Tires ... $254-306.00 Each
235/50-18 Snow tires ... $193-225.00 Each
225/55-18 Snow Tires ... $139-177.00 Each
The narrower (and taller) the better for Snow Tires and I'm sure 18" wheels are cheaper and easier to find than 19's.
I've actually got 215/65-17's on my 2011 V6 ... tallest tire Ford put on 2011-14's (28.00" vs. 27.25" for my factory 235/50-18's)
I've got 18" snow tires on cheap TireRack brand wheels (the "Sport Edition" center caps I could do without, but other than that they're fine). I want to get a full-sized spare for my 19" summer tires, and figured a steelie would be a cheap and reliable thing to stick it on.