How to find and purchase a spare tire for a Prius Prime 2017/2018

I bought a donut spare for late model Corolla from a local junkyard for $25. Drove with it a bit and it worked fine. I keep it behind the front passenger seat in the footwell, with a vinyl cover over it (exterior cover for small wheel, a la a Jeep's outside spare). I rarely have more than 2 passengers, and just throw the spare in the trunk if I do have 3. I would like to secure it somehow so it doesn't fly around in a crash, but haven't gotten around to figuring out how.

I also have a plugging kit and a good 12v pump in the car, as well as the original/factory slime/pump kit, so I'm pretty well prepared for a flat tire apocalypse .

 

You can just jamb the back of the seat against the spare.

 

I found a cargo strap from an overhead carrier I used 2 or 3 times in the past, and a cargo net from my defunct Gen2, and tied it to the headrest of the back seat. No flopping.

I thought they left the spare out to reduce weight and improve mileage (same with the divider in the back seat-- the don't want three people back there)

 

no, there just wasn't any room. heck, there wasn't even enough room for the battery. the space under the rear center console gets a buffer battery for the euro solar roof.