Do the size of your wheels affect gas mileage? I wanted to get bigger wheels, but don't want my mileage to decrease.

Generally speaking yes, they do. Larger Diameter wheels tend to weight more than smaller diameter wheels - assuming the tire diameter stays the same. The higher weight results in more inertial forces and requires more energy to accelerate. Of course with a hybrid, some of that increase rotating inertia will be recaptured during braking, but the overall effect is likely a decrease in fuel economy. Might be best to retain your stock sized wheels.

Hi,
The generally, larger tires have these effects:

1. larger diameter - leads to a heavier tire with greater (inertial) moment. This tends to require more torque and leads to more frequent ICE operation.
2. larger width - leads to more tire contact with the road. Although offset by lower pounds per square inch, it isn't clear that this reduces rolling resistance. Also, the greater mass again requires more torque.

The real problem is it could cost $300-$500 to run the experiment and if the results aren't good, that money would be hard to recover.

It might be cheaper to see if you can rent a car with wheels and tires of the size you want to test; swap wheels; and run the experiment. Then swap back to your original wheels and return the rental. Depending upon price, you should be able to conduct the experiment for just one day's rental. If you do change the wheels, pay attention to the odometer readings and their impact on MFD display values.

One data point is the 'touring' Prius has larger wheels and is reported to have lower MPG. But other things could contribute to this effect. I'm not trying to discourage you from the experiment, just sharing what little is known.

GOOD LUCK!

Bob Wilson

Operation Iraqi Oil Freedom:

Automatic, stock, project car.

My other 1500 cc car:

Automatic, stock, backup car.
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I am quite confident that larger wheels will always decrease fuel efficiency if they are heavier. The same is true with larger diameter tires and larger width tires. The best efficiency would be if a vehicle had really large diameter low profile tires like you find on a racing bicycle. However this style of wheel and tire is not practical for an auto. To confirm my contention, just look at those experimental solar cars. They use wheels/tires that resemble a bike more than a conventional automobile. Larger diameter, thin wheels with really small cross section tires.

Thanks guys! Do you know if it's possible to fit 20" wheels on it? The more I think about it, I'd rather have the "looks" than the mileage.

Search the net and read about the Prius that set a land speed record for hybrid cars. To get a higher speed, they put larger diameter wheels but had to make some serious modifications.

Bob Wilson

Operation Iraqi Oil Freedom:

Automatic, stock, project car.

My other 1500 cc car:

Automatic, stock, backup car.
Free speech, dialog and knowledge thrives without the poison of SPAM.