17" Vs 15" gas mileage

Welcome to Prius Chat Gail! Keep this in mind....weather plays a significant role in your gas mileage. The warmer it gets, the better your MPG's will be. As far as your wheels go....the 15"s weigh less than the 17's which would be less weight that the car has to get rolling and keep rolling. Do I have exact numbers...NO, but I would say that slightly better MPG can be achieved with the 15's.

 

Welcome aboard, and congrats on the new car.

Although this has been discussed (to death), I'll save you the effort of doing a search. The 17" wheel cars have ~1 MPG less than the 15" wheel cars.

 

There are a lot of things that affect mileage!
That being said,I think 46MPG on a new car is great.
should get a little better over time. It has been said by some here that the larger wheels and tires do lower mileage just a bit!
To me it's worth it not to have to look at those cheesy wheel covers
that they put on the II -IV! Toyota could have done better.
Don't worry be happy!!
http://priuschat.com/forums/gen-iii-2010-prius-main-forum/77753-you-happy-your-pkg-v.html

 

Gailmiller10: We got a 2010 Prius II for my wife a little over a year ago and recently got a a second 2010 Prius that is a V. Although people claim that there are differences in the fuel economy between 15" and 17" wheels, I am not convinced that any consistent difference can be seen between our two cars. Other than a tiny difference in tire circumference and aerodynamic characteristics of the tires and wheels, I cannot see how a difference in the 15" and 17" wheels would alter mileage. I have read claims that differences in the weights of the tire and wheel combinations predict differences in fuel economy, but the logic of these claims seems flawed because the wheels aren't spinning in the air. Our tires maintain contact with the road during, virtually, all of our driving and the electric motors and ICE push the weight of the entire car, not just the wheels and tires. Although I haven't bothered to check the exact statistics, I believe that differences in the weights and economy of the two Prii are determined more by the level of fuel in the tanks, number of passengers, and whether we run the A/C or not, rather than differences in the weights of the II and V packages. We are in So. California, so cold temperature is not a critical factor. I usually get slightly better mileage than my wife, regardless of which Prius I drive. I attribute this to the attention that I give to monitoring and manipulating the hybrid technology, seeking maximum efficiency, while my wife drives the same way she did in non-hybrid cars that we have owned. Her driving is more relaxed and she is much more inclined to run the A/C than me, while I tend to ignore comfort and speed, favoring economy. We both average MPGs in the high 40s to mid-50s, regardless of the Prius, with the difference dependent more on driver, route, and A/C use than wheel size (Prius package) driven. My recommendation is that you enjoy the features of your Prius V. Whether you drive for economy or relaxation and comfort can depend on your usual temperment or the mood of the moment. Regardless of your preference, you'll get great mileage in your Prius.

 

Don't worry about it. You have nice rims.

 

I'd think that almost all of the 'difference' between the 15's and 17's is the fact that the 17's will almost by definition be more performance oriented .... which generally means a softer compound .... which translates into more rolling resistance ... which in turn translates into lower mileage .... to say nothing of the increased contact patch area, which also creates friction, and resistance, thus lowering mileage a bit.

REV

 

Aloha and Welcome Gail! I am not doing anything special but have averaging in the mid 50's according to the Cons. on the MID. That comes out in the low 50's when I divide it. I am also driving in a tropical environment, I do not have the cold to contend with. Enjoy your Prius.

 

Mad-dog-one, you completely ignored friction and rolling resistance. That is the biggest reason the 17" wheels contribute to lower mpg when all else is equal. Now that there are LRR 17" tires available, the difference in mpg is less that would have been expected even 3yrs ago. Revhigh pretty much covered it.

 

You are correct; I didn't consider differences in the tire footprints or hardness of the rubber that would alter to rolling resistance. I assumed these were similar for the 15" and 17" wheels, but that may be a naive assumption. I appreciate Revhigh's and your comments. Even if the rolling resistance is different between the stock II and V wheels/tires, our non-scientific observation is that driver preferences and practices predict more MPG difference than the package II and V differences.

 

It appears to be more than 1mpg loss for me if all the graphs around here are accurate for gas mileage on 15" rims.

Where they say I should get 55, matching the same parameters I get 50 for instance. I think it does average out better than that over time, but it is more than you'd think.

My lifetime average is only 45mpg, moderate climate, rural road driving mostly, 47MPH average on my commute. My best tank ever was 48.5MPG and 500 miles. (which is so awesome compared to most cars it's not a biggie, but I'd like to average over 50MPG like others!)

 

The contact area between the tires and road is larger with the 17's (they're wider), and the weight of the rim and how the weight is distributed is different, so more friction and it takes more power to actually accelerate the wheels.

I do agree driving style does make a huge difference, more than the tires.

 

I agree with ya. The driver and the commute conditions will have the largest effect on mpg. One huge consideration is not the size of the wheel but the tire used. A wide performance oriented tire can really kill your mpg compared to a narrower tire designed for maximum mpg.

Back When I swapped to 17s on my GenII in 2007 or so, there were no LRR 17" tires available. I bought a run of the mill ultra-high performance 215/45/17 and my average mpg dropped by 4-6mpg. The new wheels weigh nearly the same as the stock 15s so I can only assume the tire is to blame. The 17" tires also weigh more than 15" tires by about 3-4lbs on average. I've swapped back and forth between the 17s and 15s many times and the mpg always drops by this amount no matter the season.

I think the new LRR 17s are really helping fix the big loss us early upgraders suffered. Hell even people who stick with 15s but choose bad tires often report a 4+mpg loss even after break in so I am a firm believer in the big effect tires play in mpg.

 

That's because EPA rules allow the same estimate to be used across the board if the same engine is used. According to EU (European) estimates, the 17"-wheel Prius has a ~1.8 mpg hit compared to 15"-wheel Prius.

Yet the stock 17" tires don't appear to be LRR. The OEM Bridgestone Turanza EL400 are "LRR Ecopia" only in the 175/60R16, 195/55R16 and 215/60R16 sizes and the OEM Michelin Pilot HX MXM4 are "LRR Green X" only in the 255/55R18 size. Know of any good replacement LRR 17" tires and do you know if they have the raised rim protector (which would be my requirement) in the 215/45R17 size?

 

I would love to see a true test with those above mentioned tires and a stock 15" combo.

TheEcopia Ep100 is now available in a 215/45/17.

 

One issue with your assumptions is the anecdotal evidence you're relying on, as highlighted in red above.

On a site like this, you're going to get reported MPG figures that are biased toward the high side, for lots of reasons (bragging rights, exaggeration, hypermiling, etc.). FWIW, my average for the 20 months / 19K miles on my Prius is 46 MPG.

The difference I quoted in my previous post is based on the Toyota UK published numbers, which differentiate between the 17" and 15" wheel cars, unlike the US EPA estimates which don't. Translated to US numbers, the 17" wheel cars get 1.24 MPG less than the 15" wheel cars.

 

I have read several posts attributing differences in fuel economy to differences in the weights of the 15" and 17" wheel/tire combinations. I don't buy this explanation, given that the drive wheels/tires push the weight of the whole car, not just spinning the drive wheels in the air. The weights of the wheels/tires is negligible compared to the weight of the rest whole car and would be off-set by a passenger. If all other conditions were precisely equivalent, shouldn't cars having identical weights (measured with their respective wheels, tires, and passengers) get the same mileage, whether they have 200 lb 15" or 300 lb 17" wheel/tire combinations? In this scenario, the only drawback that I see for the big wheel Prius would be the requirement that the 100 lb cheerleader (passenger) would be riding in the Prius with 15" wheels. On second thought, disregarding the equivalent fuel economy, maybe the 15" wheels do have an advantage, on the drive home after the game.

 

This isn't true, as unsprung weight is different from sprung weight. However, unsprung weight still isn't a big factor as evidenced by members who've swapped out their factory 17"s for lighter 17x7 wheels and saw no or little mpg boost, depending on other factors (aerodynamic, etc.).

 

I rented a 2010 II. Drove it over 1000 miles in different driving conditions. I then bought a 2010 II, but removed the tires/wheels before I even hit 50 miles and replaced them with aftermrket 17s. According to the computers in both cars, which is obviously not scientific, the 15s were able to achieve much better mileage. I can't even come close to the numbers I was getting with the rental in my new car.

My guess is I am probably taking a 6 mpg hit. Sounds like alot, but that is only about 60 miles per tank. Im sorry, but those 15s are just plain ugly.

I have about 3k miles on the car. Calculated, I am getting right at 47mpg every tank. Display shows 50mpg.

 

Your assumption is incorrect. I have links that describe why but I'm using my phone to post and it is not forum friendly. 32colors pretty much summed it up and the short of it is that any weight added to the vehicle will reduce economy but unsprung weight is the worse. It simply takes more energy to rotate more mass.

U nlike some people on the forum, I've tested this idea on my trucks and my Prius so I'm not speculating. I've swapped back and forth between 17s and 15s many times and observed the changes. I still feel the difference is mainly from tires and not weight.