People talk about how heavy the stock V rims are, but it's only a 1.8 mph hit compared to the factory 15". Forum members who've upgraded to lighter 17"-19" rims still see the same (or worse) mpg hit due to the less aerodynamic design of the aftermarket rims compared to the factory 17".
Sorry to bring this back from the dead. I did not want to start a new post. I have 3 sets of wheels for my hond fit. Looking to get a Prius for the Fiancee. One set of my fit wheels is Volk TE-37. 17x8.5 and weigh 13 lbs each. If the weight for the 17" OEM prius wheel is really 24 lbs, then 44 lbs all around off the wheel should be a major improvement. (that is of course if the tires are the same) no idea what it will do to fuel economy.
I think the biggest hit to MPG is not the rim weight but the tire composition and style. My 17" rims weigh as much as my 15"s but the tires are completely different and the 17" tire weighs more. So when comparing the weight between two different sized wheels please don't forget to add the weight of the different sized tires. In a nutshell, I lose about 6mpg when I swap from my stock 15's with dB Super E-Spec tires vs. 17" Centerlines with Kumho Ecsta tires (high performance).Weight is about 6lbs or so more for the 17's. I can't remember exactly.
I think the MPG hit between the 15" and the 17" has less to do with the additional weight and rather due to the broader width of the 17" tires. If you swap the 15" with the 17", the extra metal adds 3.6kg x 4 = 14.4 kg - this is slightly less than 1% of overall mass of the Prius (1445kg in the base trim with 15" in Germany; weight will vary depending on country specific trim). The rubber is probably weighing the same, since the 15" tires are narrower but higher (195/65), while the 17" are wider, but thinner (215/45). So what I think instead contributes more to the MPG "hit" is the fact that 17" wheels are broader, providing better grip, but much more rolling resistance. The weight of the wheel itself does not have an hit in MPG per se, rather the overall weight of the car (the mass that needs to be moved). So I cannot imagine that 14 extra kg are hitting MPG significantly if at all... The MPG "hit" is rated in Germany according to EU regulations to 0.1L/100km in suburban driving (ie 3.8 to 3.9L/100km, or 60.3 to 61.9MPG - 1.6MPG difference, or +2.6%) - highway and urban drive remain constant to 4L/100km: in the former case, likely because wind resistance has a much higher effect than wheel size/weight; in the latter case because urban stop&go driving has a bigger effect on FE, than, again, the overall difference in weight due to the wheels. In suburban driving the "hit" comes from the extra rolling resistance. The best way to consume less is to: drive slower, drive smoother, keep tires well inflated, keep trunk empty of crap rolleyes, or...drive less!
I weighed my stock 15" wheels with Yokohama tires & they were 34 lbs. I figure that if I went with 17" wheels than I would get 205/50R17 since they will make the speedo accurate & would be narrower than a 215/45R17. I would still like to keep the weight down as much as possible though too.
We've got the Canadian Touring model, similar to the US V as far as having the 17" wheels/tires. Purchased last November, within a week a swapped to Michelin X-Ice in 195/65R15 on steel Corolla rims, which I pressured to 42/40. Two weeks back I swapped back to the stock wheels, which in our case came with Michelin Pilot HX MXM4 215/45R17, and set the pressures 42/40. Since the swap, the in-dash mileage display is about the usual, considering the driving mix (currently 4.7 liters/100km). Our usual driving consists of a mostly short trips, but the last 2 weeks have had a somewhat higher percentage of runs to neighbouring communities. My seat-of-pants impression of how much the car rolls on is that it's about the same, maybe slightly more reluctant. I've also noticed the ride is a little less "forgiving", going over speedbumps, with those pressures: the low profile 17" have less give. Now this is going from a snow tire, albeit a LRR one, to the stock tire. I suspect if I put in stock 15" rims and something like Bridgestone Ecopia EP20 195/65R15 (Prius in our area are getting these as OE 15"), there would be an improvement, maybe taking the above value 4.7 liters/100km down to 4.4~4.5.
I wonder if the lighter rims are as strong as the heavier rims? I myself would put safety first before MPG. I just picked up my 2013 Prius2 that came with the OEM 15" rims and Yokoma tires. In my purchase deal I requested 17" rims with Michelin MXM4 tires. On 3 hour drive home the ride was smoother more responsive and don't think MPG suffered any. I really can't compare as my wife drove home on Tuesday from the dealer w/ the OEM rims and tires while not using the cruise control but the display readings are different. First trip home from dealer the miles to go before fill-up was 409 but we filled up before heading home this evening with new tires and the before fill up display showed 1200 miles. So IMO rim weight is questionable.
Doug, please get more seat time in your new Prius before stating the above conclusions. It's a well documented fact that you'll lose mpg with the 17" wheel upgrade and that more weight doesn't always equal more strength or safety. In fact, more weight increases stopping distance and hurts suspension dynamics. You're also confusing the distance till empty gauge with something else. You will not swap wheels and go from a DTE of 409 to 1200. Just drive the car and enjoy it for awhile. These threads will start to make more sense.
I realize I need more seat time. As for the DTE the dealer filled it up? so I am not really satisfied with the readings but just taking notes. Driving to Missioula Montana on Tuesday and just filled the tank so waiting to see how the power mode works out (a big mountain to go over.) I realize wheel weight affects mileage as well.