Tire size info for 2015 Prius C

The Four version was offered with a different optional wheel and tire combo. If I remember right, it was actually a 16" wheel, not 15". It also had a different steering rack and a much wider turning circle than the regular c to keep the tires from rubbing on the fenders.

 

The recommended tire size(s) are shown in Owner's Manual. If there's more than one size they will INVARIABLY have the same (or very close) outside diameter. The two tire sizes you mention are different; the (unauthorized) larger OD alternative you mention will:

1. Raise the car.
2. Throw off the odometer.
3. Throw off the "gearing".
4. Fool the speedometer into thinking you're going slower than you are.

 

Yeah increasing from 175 to 195 (tire width), and considering the 65 number (tire width to height ratio, as a percent), the tire outside radius increases by:

(195-175)x.65

Which works out 13 (mm) increase. This is significant, well out of spec. Minor diff's of 1~2 mm are acceptable, but not 13.

For some 13 would be acceptable, but it's into uncharted territory, not condoned by Toyota.

Besides the aforementioned downsides, it'll make the car take corners a little different, reduce stability, basically make it more tippy.

 

I have done some research into this, as I am thinking of going to a 195mm section width tire when the time comes to repalce the stock tire. I have found that 195/60/15 is only +0.8% from the stock tire size, so will have less of an inpmact on the odo, etc. The question I have not been able to get a clear answer on is about putting a 195 mm tire onto the 5" stock wheel. The tire mfgrs. I have looked at (Continental, Yokohma) say that this size tire can fit on the 5" wheel, but other sources say that the minimum wheel width for the tire is 5.5 ". Anyone with experience with this?

 

It's been a long time since I installed tires for pay, but I would always trust the fit application data from the manufacturer. If (for example) Continental says theirs will fit a 15x5 rim, trust them.