One reason for the 2011 Cruze’s excellent fuel economy is its wheels

Discussion in 'In the News' started by xcel, Apr 20, 2010.

  1. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    [​IMG] Alcoa forged aluminum wheels to be exact.

    [fimg=right][/fimg]Wayne Gerdes - CleanMPG - April 20, 2010

    2011 Chevrolet Cruze – Its 40 mpg highway has everything to do with three, yes, three OD geard, a reasonably efficient 1.4L Turbo and some reasonably light Alcoa alloy wheels ;)

    Alcoa Automotive Wheels has been awarded the wheel program for the 2011 Chevrolet Cruze Eco. The lightweight wheels help the vehicle to achieve outstanding fuel efficiency. Chevrolet recently announced a segment-leading estimated 40 mpg on the highway for the Cruze Eco when equipped with a manual six-speed transmission.

    “Alcoa is pleased to supply forged aluminum wheels for Cruze Eco. Closely following the launch of our Volt wheel program, the Chevrolet team pursued a wheel providing light weight performance that would further extend fuel economy for this latest vehicle,” said Victor Marquez, Vice President and General Manager – Alcoa Auto Wheels.

    Alcoa’s focus on design, engineering and production techniques are meant to lower the overall weight of the wheel. Forged aluminum wheels by Alcoa provide increased strength, durability and are typically greater than 20 percent lighter than a comparable cast aluminum wheel. The seventeen-inch wheels fitted to Cruze Eco weigh just 17.8 lbs.

    Light weight forged aluminum wheels not only have a mass reduction effect that reduces emissions and fuel consumption but also further improves driving performance and efficiency by reducing unsprung weight. Less rotational inertia is required to accelerate and decelerate the wheels. Additionally, less mass in the wheel allows for mass reduction in adjacent, unsprung components such as brakes, steering and suspension. Forged wheels offering light weight benefits are the catalyst for a paradigm shift in mass reduction and continued improvement in fuel economy and emissions.

    “Alcoa is honored to be working closely with Chevrolet to continue to provide light weight wheel solutions that benefit the consumer, the economy and the environment. If we can also enhance the driving performance, then it’s a success on all fronts,” concluded Marquez.

    The application is the latest of a growing number of Global OEMs converting to forged aluminum wheels from Alcoa. Wheels for the 2011 Cruze Eco are forged at Alcoa’s Cleveland, Ohio (US) Works Plant.

    Now if GM would have spec’ed 15 or 16” rims and tires instead of the larger and heavier 17’s for the upcoming Cruze…
    Last edited: Apr 21, 2010
  2. PaleMelanesian

    PaleMelanesian Beat the System Staff Member

    17.8 lb?!! The 13" honda VX rims were under 10 lb, and the HX and Insight 14" rims were in the 10-11 lb range.
  3. WriConsult

    WriConsult Super Moderator

    Yeah, but Honda's lightweight rims weren't as as cool looking as the Cruze's. :rolleyes:
  4. Bruce

    Bruce cheapskate

    ...and they probably weren't eggbeaters like the Cruze's either.

    I expect any supposed weight reduction is going to be lost in aerodynamics and increased RR from low-profile tires.
  5. phoebeisis

    phoebeisis Well-Known Member

    Smart move-weight kills-A 17.8 lb 17" wheel is pretty light.I actually weigh wheels(best place is a Post office lobby scaleon a Sunday), and 17.8lbs is probably 6-7 lbs less than an average cast aluminum wheel, and 12 less than an average steel wheel.

    The 17" 7.5 steel wheels on my Titan were over 31lbs- factory aluminum 25.5lbs- Centerline forged 20.5lbs. Car wheels will be lighter of course.

    I wouldn't bet that those wheels have a lot of drag.Safe bet they have been tested, and despite the looks probably have a decent drag coefficient.

    Those special Honda wheels are for much much lighter vehicles- vehicles maybe 65% of the weight of the Cruze. They are also tiny which frequently means more of other sorts of resistance/friction per mile.

    I'm impressed-GM is finally using its very good engineering talent to produce a good small car.Not a typical GM "cheap out' POS like we have gotten for the last 40 years when it came to a economy vehicle.
  6. saturnsc2

    saturnsc2 Well-Known Member

    does anyone know why gm uses such huge emblems now on all it's cars? The things are the size of a dinner plate haha.
  7. Nevyn

    Nevyn Well-Known Member

    Because Honda did it first?

    I'm not 100% sure I totally get why the whole 17 thing is bad. I realize that it's kind of large, but beyond that I'm clueless. 16's with a taller profile tire would be better? Why/How so?
  8. PaleMelanesian

    PaleMelanesian Beat the System Staff Member

    I'm ignoring the spokes vs rubber sidewall tradeoff. The rubber is likely slightly lighter than metal alloy, but I'm not sure how much.

    Think of where the mass of the rim is. It's mostly out on the edge, like a donut, away from the centerline. The rotational inertia for a donut is a function of the radius CUBED. Looking at just this rim, changing from 16" to 17" is 20% worse inertia. In addition, there's the extra mass needed to create the larger rim.

    6% more rim mass, but probably more if it's wider as well.
    20% more rotational inertia, resisting any acceleration/braking efforts.

    compared to a 14", it's 79% worse, or nearly double.
  9. Nevyn

    Nevyn Well-Known Member

    Ah, that's helpful. Thanks for that.
  10. basjoos

    basjoos Well-Known Member

    If you drive with minimum use of the brakes, then lowering rolling resistance has a much larger effect on mileage than lowering wheel weight. Wheel weight only hurts you when you hit the brakes, otherwise that increased rotating weight is just added inertia to keep you rolling further. I have OEM steel wheels on my car and, as far as I can tell, it hasn't hurt my mileage any.
    Last edited: Apr 22, 2010
  11. PaleMelanesian

    PaleMelanesian Beat the System Staff Member

    I also have steelies.

    I think it does work against you if you drive P&G style, since it's working against you in both acceleration and deceleration. Steady speed would be as you described.
  12. Nevyn

    Nevyn Well-Known Member

    Wouldn't it be working FOR you in a glide? Heavier means more inertia, which means more resistance to slowing down?
  13. basjoos

    basjoos Well-Known Member

    Just like vehicle weight, wheel weight only hurts you if you have to do any braking, otherwise you get back the additional energy put into accelleration in the form of a longer coast.
  14. PaleMelanesian

    PaleMelanesian Beat the System Staff Member

    That's probably true. I'd rather have the lighter weight, though, because this is the real world, and braking happens. ;)

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