Fuel Economy on 17's

see my fuelly profile in my signature for details! generally my commute is 3 miles city 32 miles hwy (no traffic mostly) each way + mix of city and highway of varying conditions on the weekends, which comes out to around 15-20% city driving.

 

I don't think much can be said from only two tanks of gas on a brand new car with a brand new driver. There are way too many variables.

It appears most owners with 17s/18s average 44-48mpg. There are some who manage to hit the low 50s as an average. It is quite rare to see anything higher than that after a full year of driving because while summertime mpg is pretty decent with 17s, winter hits and crushes mpg. Those living in mild climates are affected the least but there is usually at least a small hit.

For those who don't drive many miles per year the economic hit from 17s/18s isn't so bad. For people like me who hit 30k-40k a year the hit is just not worth the style points.....

 

Np Homie.

I do not doubt your ability to stay above 50mpg but you cannot rid yourself of the loss. You will always do better with the 15s and the better you drive the more the gap widens. LOL

 

F8L is spot on like usual. I have done almost a years worth of switching between my stock 15s & 17" aftermarket & although I love many things about the bigger wheels, in terms of optimum FE, you cannot beat the stock 15 inch that non-prius V(Five) comes in. From my experience & just being conservative, mines about a 5-6 mpg difference & again I'm being conservative. That being said, I do have a little wider tires than most w/225 series. Still, I figure at the worst it would negatively affect it 1-2 mpg. over the 215 or 205 width. For you(VegasPrius), the change wouldn't be as dramatic as you had the V(Five) w/ the stock 17". Nontheless, this is a good topic of discussion that I'm sure more people will express their opinion & knowledge of.

 

Interestingly enough, my in my first extended drive on my Prius 5 OEM 17s (with Toyo Proxes 215/45/17), I actually noticed a slight increase in MPG (I normally average 50-55, but averaged 58 on an 80 mile drive). Based on what I noticed on the iMPG gauge, I probably suffered a MPG hit during acceleration but I think I had an easier time holding the iMPG above the 50 MPG barrier when the car was up to speed. Perhaps I was more cautious about my MPG on my new rims and my driving behavior reflected that, or maybe it was a MPG indicator anomaly, but I thought it was interesting that I was getting better MPG on my 17s versus my 15s.

 

^The rolling resistance of the before and after tires could be a factor: maybe your new Proxes are lower RR?

Also, the smaller OD of the 215/45R17 makes the car think it's gone a bit further than it actually has. If you look up the revolution per mile for that tire, and the stock 195/65R15 you can work out the percentage difference. It's not that much, at most 1%.

All things being equal, the consensus is you will take a hit with the 215/45R17, around 2%. That would be ignoring the different OD's, just driving a measured distance.

 

Yes, that's real good for 17's.

 

So glad I found your thread! I have about 650 miles on my package five and according to the computer I'm getting 45 mpg. I thought I was doing something wrong. Never knew the stock 17's would create such a hit to fuel economy. I was thinking about switching out the stock rims for a lighter set while keeping the stock tires. Could I expect to gain a couple mpg's if I did this?

 

FWIW, I swap our OEM Michelin Pilot 215/45R17 for Michelin X-Ice 195/65R15 Snow Tires (on steel rims) every fall, and mileage stays about the same.

 

Your fuel economy numbers stay the same from summer through winter with that swap?

 

Well, once the temps start dropping so does mileage, but what I'm finding the mileage around the transition period is similar. In other words: the snow tire penalty and 17" penalty are about the same, at least for me.

The X-Ice have LRR in the description, but still I don't think they're going to deliver the mileage of an all-season LRR tire.

 

Take a look at my profile. Last 5 fill-ups I get quite stable results, climbing a little up with hot weather temps. In terms of mpg it is around (4.7 l/100km = 50 mpg) or slight below the target. Considering RON 95 fuel, short trips (5 - 6 mi) I'm happy with this result.
Stock 17" rims with OEM summer tires => Michelin Primacy HP 215/45/R17.

Details: Toyota - Prius - Prius ZWV30 - Spritmonitor.de

Considering my driving and road profile (short trips, traffic jams, avg speed around 16 mph) I would be happy to get constant, stable 5.5 l/100km (42.7 mpg) in winter (with Goodyear UG winter tires).

 

At this point I'm pretty sure I could manage mid/high 50s on 17s with summer weather but it's still a far cry from what I get on 15s. I was getting about 53/55mpg just before summer hit and before I figured out how to really drive this car. Unfortunately the 15s offer MUCH better mpg numbers for my driving situation so I stuck with them and sold the 17s. Now 67-68mpg is doable without any pulse & glide sessions although 65mpg is the norm.

 

how about this for mileage on 17", my package 5 prius w/o ATP on factory toyos...

 

Quite outstanding!

 

Note that the OP is from Japan, and probably doesn't drive at the higher speeds that most Americans do.

Also, I see a big MPG hit when I put my Blizzaks on with stock 2010 15" Prius rims, like 10% or more. I have Ecopia 100's on 15" rims for the rest of the year.

 

I've run almost 59,000 miles on my original Toyos (on the 17" OEM wheels), and the results have been great. I have slightly lower fuel economy than on my Gen II (with 15" wheels), but the trade-off in control and driveability has been worth it to me. I would do it again, and I will repeat it when I buy my first set of replacement tires.

You can see in my signature the lifetime mileage numbers coming from the multi-information display. For FE based on actual fill-ups and calculations, please see my recent post: 125 Fill-Ups; 58,000 Miles; ~50 MPG.