Car & Driver Plus-Size FE Results

[tasdrouille]

Well, they just confirmed what we knew.

I would have liked to see a 195/70R15 and 205/75R15 tested.

[Allch Chcar]

C&D hasn't been very good at scientific testing. But I'd like to see some testing for same tires and wheels sizes with different wheel weights too, just from a nerdy Point of View. A 10% change in MPG from the base tire to the premium tire is pretty significant. It explains a lot about Car companies favoritism for base models with steelies despite options for aluminum pizza cutters being the first available upgrade. Most companies would pay $$$$$$ for 1% better FE while aluminum wheels can be had for $150 more from the base car (as an example not a fact). When people spend $10k at least for a new car, cheap aluminum wheels are probably one of the first upgrades unless they just don't care at all, lack of options from the Dealer/Company, or they plan to get aftermarket wheels anyway.

[Big Dave]

This squares with pickup truck experience. Bigger diameter = lower mileage.

Why do the best MPG cars use little tires? Think their engineers know a thing or two?

Rotational moment of inertia goes up with the square of radius. This increases the rotational moment of those four "flywheels" at the corners. Everytime you accelerate, you have to pour energy into those flywheels to speed them up. In a perfect world a generator recoups that energy. That is part and parcel of a hybrid's MPG superiority.

[Frank Lee]

Didn't I read that the Cruze high mpg version runs 17s?