Different MPG with 17" vs 15" Rims GenIII

There is a slight difference in MPG. There is also a slight difference in circumference, but I am not going to go to the trouble to look it up. There are websites that will calculate it exactly.

Here is one of them:
Tire Diameter And Circumference Calculator

Put in the sizes and it will tell you exactly what the circumference of each tire is. I think the difference in MPG is more related to the total package, weight, etc and not directly to the circumference.

 

Following is the very special spy shot taken from the Toyota's internal document.

17" average combined FE = 67.3 mpg
15" average combined FE = 71.1 mpg

Ken@Japan

 

For the stock 15's, the diameter is 25 in whereas the 17s are 24.6 in. I switched my stock 15s to the OEM 17s, but not with the LRR tires. As Paradox quoted, the 15s do have less rolling drag, so acceleration is a bit more responsive than the 17s. I'm not really comparing apples to apples since my current 17s do not have the "stock" tires, but I am getting anywhere from 4-6 mpgs less than with my 15s.

As for the 10" rims, I would think there would be a severe handling tradeoff and probably accelerated tire wear...

 

With low rolling resistance tires on the 17" wheel the MPG difference should be approx. 3-4mpg lower than the 15" wheels if all else is equal. With a non-LRR tire on the 17" wheel the difference in MPG will be magnified and can be as high as 5-6mpg if you compare a high performance 17" tire vs. a LRR 15" tire. I've swapped back and forth with a combo like this for the last couple years and I always lose at least 4mpg when I put the 17"s on.

 

Yes, the bigger rims get worse mileage, typically quoted in about the 2 mpg range. The typical reason given is additional weight, especially since it's unsprung weight, plus because of the inertia of getting them spinning every time you start moving.

 

Based strictly on the car's display (I don't calculate my mileage like some others), I've been getting .1 less mpg since I installed my 17" wheels/tires, which was several hundred miles ago. That's nowhere near the 2-4 mpg drop suggested here. I'm assuming I took a lighter hit because my new tires/wheels weigh less than the stock set did.

 

I have about a 56 mpg average over about 12000 miles. This includes mid 40s in cold weather and approaching 70 in the middle of summer.
I'm not a physicist and I don't play one on TV; but my guess on the difference between 15 (I have on my III sans wheelcovers, with centercap) and the 17", is a combo of weight and tire width (15x195 vs 17x215). I suspect the width is the real killer due to rolling resistance, anyone know of a 195/52x17??
Tony Renier

 

I highly doubt you would be able to calculate a difference down to one 10th of a MPG. You either have not tracked enough miles and/or you are not accounting for weather or conditions that have changed. That being said, a lightweight 17" wheel that weighs equal to or less than stock coupled with a narrow tire should enable you to maintain stock-like MPG. Unfortunately the stock 17" wheel weighs significantly more and are wider than the stock 15" wheel which is what is generally being described in this thread.

 

My apologies. I did not know this discussion was limited to stock wheels.

 

You might try a search--this topic has been thoroughly discussed.

 

You guys are blowing Hot air w no real data to backup 15 yields lower rolling resistance than 17 inch, so Why Tesla, BMW i3, volt, other hybrid , EV makers put 15 inch wheels/ tires on instead do 18/ 17 if 15 will give 3-5 mpg more? Toyota dump 15" they are cheaper and incease their profit margin by hundreds of millions $$.

 

Why would you bring 5 year old thread back?

 

Perhaps you might give us some engineering data:

• relative weights of net weight change of 15"+tire vs 17"+tire - probably needs to be a three count sample set
• relative revolutions per mile of 15"+tire vs 17"+tire - again, needs to be at least a three count sample

To be complete, you might compare raw weights of:

• 15" alloy wheel (stock Toyota)
  
• 17" alloy wheel (stock Toyota)
• 15" carbon fiber wheel (after market)
• 17" carbon fiber wheel (after market)

Rolling resistance changes with vehicle weight as well as braking inertial losses. So it would help to know if any particular weight change of the wheels+tires as a function of tire size. Also, the revolutions per mile relates to the bearing drag. Then look at after market wheels just to see if the change is larger than weight loss of fasting for a couple of days.

FYI, if the weight changes that measure a fractional percentage of the 3,042 lbs (1,380 kg) vehicle weight made that much of a change, I would expect to see Prius without rear seats and the rear storage area stripped. In fact, strip out everything that has weight and mass not needed for vehicle safety and the car becomes a whole lot lighter. Add to that, claiming the car should only be filled up to 5 gallons (6 lbs/gal * 5 gal = 30 lbs saved!) and everyone should fast to anorexia.

Just sayin',
Bob Wilson