Wheels and Tires

So long as the circumference of the tires are equal (or revolutions per mile) it does not matter how much is wheel and how much is tire. (except for ride quality)

 

Quick answer: No. If you do a search on PriusChat, you will find out that the 17" inch wheels/tires are in fact a tad smaller in diameter than the 15†wheels/tires. Nothing significant enough to warrant an adjustment to the odometer.

 

I am no expert on the subject but I feel your conclusion is correct. Both 15" and 17" wheels (with the appropriate tires designed for them, in line with the 17" wheel package from Toyota) will have the same rotational speed, so no adjustment is necessary.

Also, as the 17" wheels come with lower tires, you will get more road feel with them (both good and bad).

Some have reported that fuel consumption is higher with 17" wheels.

If you have test driven a 17 inch package at the dealer, you may want to know though that the steering turning ratio of the 17" wheel package from Toyota is different than with the 15" wheel package. By switching wheels, you will not get this different rack and pinion.

 

Wheel weight is a big deal. Most bigger wheels weigh more. Higher weight decreases performance. This is magnified when the extra weight is un sprung. Un sprung weight includes all parts from the shocks to the road. Weight inside the car is balance by the shocks and its impact is lessened. Heavier wheels mean longer stoping distances and longer period to accelerate. If you want higher MPG & improved performance, get light wheels. Put the car on a diet. This improves the power to weight ratio which equals better preformance.

 

One way to test various tire sizes with a given size of wheels is to use one of the calculators such as the one found at: Tire size calculator

Put in what you have now, and calculate things like revolutions per mile. Then do the same for your proposed sizes.

 

This and many other online tire dimension calculators are notorious for being inaccurate. I find it much more useful to use the manufacturer's stated revolutions per mile for a given tire model. tirerack.com is great for this, but I have also found some errors there.

Mike

 

When I had the 2005, I switched to a Scion 17" OEM wheels and 215/45x17 Turanza tires (maybe overall at least +10 pounds over OEM). I lost approx. 5-6 mpg. The rolling dia. is slightly less than the 15". No rubbing. No calibration is needed. Due to smaller dia. than the OEM, you will be driving slightly faster than what your speed shows on the dash. But, not too much to the point where you will get a ticket. Also, you may get a slightly faster start, but I don't think so because of added wheel/tire weigh in each corner. There are no ramifications on the computer.
Although Turanza was a AS tire, it drove like a performance hard riding performance tire. When I switched to Hankook later, the ride was a little better.
Also with a new size, the car actually drove like a car instead of a golf cart going 70 mpg on a freeway. I I think the golf cart would have been more stable LOL. The 15" skinny OEM tires were all over the freeway. Very unstable. I much rather gain additional safety factor along with much improved handling. Not to mention notorious, horrible, Prius understeer.

I just got a 2020 Prius Prime PHV. I just ordered the following to upgrade the looks as well as handling:

Americas Tire:
General Tire G-Max-AS, 225/40x18. 25.1 dia. (.1" over the OEM dia.), 20 pounds. same as OEM factory Bridgestone ECO tire.

TireRack:
Flow One F3, Rotary/Flow Formed Wheel, 18x8, 45 Offset (the wheel will stick out 5/8" more than OEM and still clear the strut with a wider approx. 2" footprint), 21 pounds (4 pounds over OEM).

I plan to lower the car with lowering springs to improve handling as well as the look of the car. I will post pics after the installation. Cheers!!!