Taller tyres

You may be able to use the 15" rims & tyres from other Prius models. The outer diameter is about the same but the sidewalls are taller.
You need to be sure the rims allow adequate room for the brakes though.

 

225/45 17 is 24.6"
225/50 17 is 25.9"
225/55 17 is 26.7"
215/50 17 is 25.5"
215/55 17 is 26.3"

My size is 195/65 15 and it's 25" and my speedometer is correct.
So if you go with the 225/50 17 (25.5") or the 225/50 17 (26.7")
You will have taller sides and a larger overall diameter, ih a slight speedometer error.
Note your 225/45 17 is a bit small, your speedometer is incorrect.
SAE not metric

 

I tried to post the site I use to compare tire diameters with but couldn't since I am new to the forum. A quick search though brought up multiple sites that will compare for you. I have done slight size changes that were on the same and different rim diameters with no known ill effects. Happy shopping!

 

195/80r15” is the biggest I am aware of but he needed spring spacers

 

The Prius uses the same general overall diameter tire in all versions of the hatchback. The ones using 17" wheels have shorter sidewalls. The ones using 15" wheels use taller sidewalls. If you look closely you can see there isn't a lot of "extra" room in the wheel wells for larger tires. If you use stock Prius wheels both sizes will clear the brakes just fine. Do be aware that larger tires will rub first when you turn the wheels side to side, so just because it looks fine going straight does not mean they won't rub when you turn.

If you want/need taller sidewalls your best bet is to go to 15" wheels. Some will tell you the handling will suffer, however, the 15" wheel/tire combo will be lighter, so I suspect that will offset the higher grip and you probably won't notice any great change in handling. Better in some things, worse in others in both cases (15" vs 17").

 

I didn’t know if the 17” vehicles used larger brake disks.

 

With the 17" rims you can go to 205/50R17, which is virtually identical to 195/65R15 Outside Diameter, vs (usual) 215/45R17, which is very slightly smaller.

I alternate between our (stock) 17" and 15" (Corolla steel rims) with no issues, 3rd gen though.

Was that in response to someone? just curious. Anyway, believe brakes are the same all.

Addendum: One thing though, 205/50R17 size always seem to be Extra Load (XL), fwiw.

 

On my 2009 Gen II I use the OEM 16" rims shod with 205/50R16 summer tyres, and steel 15" rims shod with 185/65R15 Blizzaks in the winter.

Here's a useful link: Tire Size Calculator