I never carried a spare tire (I have AAA). I was on my way to a Pontiac show and there was a firebird sitting along side of the road with a flat. Guy was just sitting there like he didnt have a spare. I felt bad for passing him but there wasnt anything I could do. I made up my mind then that I would carry one.
I have a couple of sets of spare wheels, so I cleaned up a 7" snowflake that I have, got a new tire installed and I carry that with me when I travel. I went to Harbor Freight and bought a small scissor jack and a 4 way lug wrench. If Im just running around town I keep them in the garage. I have a better level of confidence if I travel an hr or so away with these in the trunk.
A full size tire does fit, and there is a little bit of room for a small cooler, detail bag etc.