Bigger Wheels = Less Fuel?

[annie0000]

Bit of a ponderment that I was having today as I walked through the car park earlier.

All other things being equal e.g. same car, same engine, driver same weight etc. does having bigger wheels mean that you use less fuel as they will need to rotate less to go at the same speed - a bit like when you were a kid and moved to a larger sized wheeled bike and you didn't have to pedal as hard to keep up with your friends.

[rojash]

Making the wheels bigger would have exactly the same result as driving permanently in a slightly higher gear. An engine is at its most efficient when the gear ratio is ideal, so no, any savings made at particular speeds would be cancelled by losses at other speeds and when accelerating.

[Old_Geezer]

Any gain in distance per revolution is lost by the extra power needed to turn the larger wheel. Were it that easy the patent office would be inundated even more than they are now.

[heathfield]

My 2.0 litre Ford Cortina Mk4a was supplied from Ford with oversize wheels. (i.e. larger than standard). As with most modern cars, there was plenty of engine power to drive them. As to higher MPG, I don't think they made a lot of difference. A fifth gear might have been a better option, as was fitted to the later 2.0 litre Sierra, which had the same engine. Perhaps tire wear was less than with smaller wheels.

[annie0000]

so not so simple as it sounds then :o) - guess I wont be heading for 20 inch alloys for my Clio then with the excuse that it'll save petrol!

[beso]

Larger wheels have a lower rolling resistance so do lose slightly less energy but the difference is small.