Got a newish donut spare from a local junk yard ("We call that a bagel spare" says the guy who sells 'kosher' used parts) for $50 taken off a Nissan Altima with the proper rim specs - 16x4, 66.1 mm hole, 5 bolts at 114.3 mm ("We call that 4.5 inches"). The guy jacked up my Leaf and demonstrated that the donut spare cleared the larger brake calipers of the front wheels. A perfect fit.
I keep it in my basement. The donut has the benefit that my DW can easily lift it if she's the person who brings it to where I sit with a flat. The small scissors jack from my deceased 1997 Toyota Camry fits perfectly in the Leaf's conspicuously empty space for a jack. I also carry the Slime tire patch kit as a first defense.
My notion is that my Leaf is our second car for local use. I can use Uber or a taxi to get home to get the donut if need be. (My 2012 is too old for the three year FREE Nissan road side assistance.)
Thanks to all the posters who've convinced me to never use the sealant provided by Nissan since it'll take out a $180 Tire Pressure Monitoring System and the hose of the neat 12 volt air pump ($200 with new sealant). FWIW, the jar of sealant in my 2012 Leaf has an expiration date of 11/2016. I see no threads of folks rushing out to replace their expired sealant, LOL.
Edit: Corrected cut-and-paste typo to Tire Pressure Monitoring Sensor