Fuel Economy Puzzler

[javorb]

Thanks. Can you recommend a brand?

k & n do one but check ebay as well

 

[MHig]

Because the larger wheels are heavier than the smaller wheels, and the weight is moved further out from the centre of rotation. This means that the engine needs more power to turn them (meaning more fuel used) which reduces fuel economy. The wider tyres also add more rolling resistance which adds a little to the equation aswell.

Can't see that, Viking. There may be a miniscule increase in the power needed when accelerating but there is no effect at constant speed. Also it will be utterly insignificant compared to moving the car.
It takes very little to roll a wheel along - a tiny effort compared to pushing the whole car.