I could NOT get it to unscrew. I resorted to pliers, grasping the indented areas, and firmly pulled. I don't see that I damaged anything.
Pull on the white plug, not on the foam. I think pulling on the foam bends the plug, makes it harder to pull up. It needs a vertical pull.
Posted on Social Media this morning - a good reason to have a FULL SIZED SPARE. Sadly only available on PRIUS in Middle East. This reminds me of one, looked very similar, on my VOLVO about 2001 - I don't think a canister of "GOOP" would have helped - or a carton of canisters. Fortunately I had a full size spare - it was 841 kilometres to the nearest Tyre Service with that sized tyre.
My story ends ironically. I bought a temporary spare with wheel and shipping for $125 on e-bay. The description was this: "10 11 12 13 14 15 16 17 18 19 TOYOTA PRIUS SPARE TIRE WHEEL DONUT 17" 5X100 PLUG IN MODELS . ORIGINAL PRIUS COMPACT SPARE WITH TIRE IN GREAT CONDITION OUT OF A 2017 PRIUS. FITS VIN FU 7 AND 8 DIGIT . FAST SHIPPING." It arrived a few days after I ordered it. It looks like it has never been used. To test it, I installed it on the back axle and drove the car around the block. No problems. It fits nicely--in the box that it was shipped in--on end, on the floor behind the passenger seat. Here's the irony. iI probably won't be driving across country this summer, which was the original purpose of buying the spare, because of the pandemic that is plaguing this nation. Maybe next year. Thanks to all for the advice.
@jehbie says they "unscrew". Even looking at the business end not that clear, but looks like rotation, maybe just 90 degrees? It's funny, if you're around long enough, you have one of EVERYTHING. This is a gizmo for Gepe slide mounts, looks promising:
That would be correct - that, or even less. Now... I 'write' that or even less, but it would not pull up. I swear that, somehow, I had to rotate that one more than 90 degrees to get it to pull up and out. I don't know why as the design isn't one to be unscrewed. But, honestly, so many, many posters have written that they 'unscrew' here on PriusChat that I am left wondering if there are two different styles. Perhaps there is a style that unscrews, but I have yet to see a picture from anyone who claimed they unscrew.
Oh yeah, sorry: I was searching 2010's. It's "wrong", in that the 4th gen centre cap will be ill-fitting. There's slight variation in the spokes too. Fourth gen is this one I think? 42611-47440 Still, for temp spare? Here also is a Corolla steel rim that works, I use them on our 2010 with snows: 42611-02471