Success: Spare Tire for 2025 Prius AWD

Following the comments, tips, and advice on this forum, I was able to install the spare tire into my AWD Prius. Thank you!

Total Cost: $525.19 - Toyota has managed to transfer this expense from their books and onto mine. Kinda clever, in a sucky way.

Spare Tire: $23 -- Dropped by the local "Pick and Pull" auto salvage yard. Hunted around for a donut wheel with the correct lug bolt pattern 5x 114.3mm (or 5x 4.5in.) A quick Google search narrowed the car models to Civics, Camry, Altima, Mazda, Sonata, Subaru, and a few others. Found a great 17" donut wheel with a tire still in good shape. Might replace it just for good measure. It is 145/50R17 - so 2.04% smaller. But it would never get driven on for very long. Replacing with a Falken 155/80R17 will be a better match. (ballpark $100.) Be sure to grab the long hold down screw with the twist handle on top that bolts the tire down to the deck. Nobody wants a spare wheel flying around the car during an accident.
Scissor Jack: $3 -- Same Pick and Pull site. Be sure to find one that is fairly low-profile if using the factory foam inserts, or modify the insert accordingly.

Now comes the hard choice. Choosing between the expensive factory "fitment" solution and opting for a custom-made one. Because the factory solution features numerous airflow channels, I grudgingly opted for it. I don't want to give Toyota any reason to deny a warranty claim if something happens to the battery or electrical distribution. While I was in there, I added a bunch of sound-deadening mat as well.

All prices are from my local dealer (Roseville Toyota in CALIF.) -- which are discounted down a bit from the MSRP. Your dealer prices may vary. It took 3 days to fulfill the online order for an in-store pickup.

Protector, Spare Wheel Carrier: $43.57 -- This is the metal bracket that covers the electrical junction for the rear motors in the AWD. Part No. 51978-47010 - ($40) AND 3x flange nuts to hold the bracket down Part No. 90178-A0132 ($3.57). For any solution you choose, I recommend some form of protection around this high-voltage wiring junction. Oddly named, as it has nothing to do with the actual holding of the spare tire.
Protector, Spare Wheel - $175.50 -- The foam insert that goes on the deck floor to set the tire on top of. It also lifts the tire up slightly, keeping everything level in the back. Part No. 64778-47090. This has several airflow channels cut into it. It could easily be replicated or even omitted. You be you.

You can now bolt down the wheel, and it won't squeak or rattle. However, the rear cargo decking will easily bend down on the edges without any support underneath it. The two foam pieces going around the wheel provide a platform to support the decking.

Box, Deck Floor, Right Hand - $175.50 -- Foam insert for the right side Part No: 64995-47080
Box, Deck Floor, Left Hand - $107.62 -- Foam insert for the left side Part No. 64997-47100

These "Deck Floor Boxes" have molded cutouts for the jack, jack handle, lug bolt wrench, tow point insert, etc. It will need to be modified slightly to accommodate the air compressor and the "Fix-a-Flat" sealant bottle.

Paying $458.62 for three pieces of molded foam was pretty painful. I thought about creating molds for expanding foam, using 3D-printed pieces (which would be a lot of them due to my printer's size), or simply cutting foam pieces and gluing them together until it built up to the right shape. All of this is doable and can easily allow for the needed airflow, in my opinion.

Pics available upon request