Anyone carry a "temporary use spare" in their car?
I use a 17" spare from a '07/08 Infiniti G35. Fits in the well, clears my 13" rotors in the front too. I think it has a 145/80/17 on it (~26" tall). That's gonna be the tallest tire that will fit in the well, so if your tires are much taller than 26" you're out of luck with a sure grip. All I did was a little dremel work on the hub bore, it was a couple mm's too small. Nothing major though, especially for a spare.
It doesn't sit perfectly even with the trunk floor, the center of the rim sticks up just a little because of the curvature on the spokes. They do have a steel rim spare for the G35's as well that's a smaller rim diameter. I needed the 17" aluminum version because of my 13" rotors. You'd have to pay attention to the hub bore though.