2006 Prius Tyre & Rim & Speedometer...Check picture

Woah a minute: you're saying the second gen with the stock tire has an inaccurate odometer? C'mon man.

 

Nevertheless, Britprius, a well respected PC member, said that the 16-inch tire was used standard across Europe.
Confusion Over Correct Prius Tire Size | PriusChat
See also this thread on PriusOnline (I am not a member of PriusOnline):
Facts about installing larger diameter wheels on your Prius. - Toyota Prius Forum : Prius Online Toyota Forums
My point is simply that there is nothing unusual about having 195/55R16 tires. They are standard in Europe.

 

Did you guys happen to notice the photo of his rims has seven spokes....just like the US Touring model rims......the second picture he shows is a US Touring model...with the plastic covers installed....perhaps they look exactly like the touring model when the plastic covers are removed? Um..yeah...maybe that's why you guys have seen them before? Touring rims without the plastic covers...

 

Since I really don't feel like going outside to take photos of my rims with and without the plastic cover, here's a link to another US 2007 Touring model that has the covers removed.....what is considered a touring model here, could easily be a standard rim across the pond...

2007 Toyota Prius Touring, Package #6, Low Miles, BAD BATTERY! (Salem, Oregon) | PriusChat

 

So it looks like Gen2 Prius for Europe all come standard with the Touring size tire of 195/55 R16. Great.
This only reinforces my point and what is well know w/ mass produced things: manufactures want economies of scale.
Manufactures achieve economies of scale by having as few unique parts as possible.

Gen2 for Japan, USA, and Canada have two types of tires:

185/65 R15 = base model
195/55 R16 - Touring model​

Gen2 for Europe only the Touring size.

Toyota clearly made the Gen2 Prius (2004-2009) with only TWO tire sizes: base and touring.

Remember, OP started all this nonsense by looking at the tire that is currently on his European Prius (195/55 R16). Then incorrectly looking up the tire size for a base model Prius (185/65 R 15) on a USA website (tirerack), and wondering why there is a difference. Clearly OP did not know Europe was shipped with the USA Touring size ONLY. And OP did not know the USA had a BASE and TOURING model.

 

OOOOOOO. Did not know that. I have only seen those "naked" Touring rims a few times.

Too bad Toyota didn't give you Touring folks the nice Persona rims that came on the Gen3 Prius.

 

And the guy still hasn’t looked at the sticker in his door jamb that tells you what tire and rim size the car came with.
It doesn’t get easier than that.