Do Larger Tires Get Better Gas Mileage?
Posted by The Happy Rock on September 9, 2008
Frugal science question of the day.
Do larger tires equate to better gas mileage?
Discuss. Let’s pull out our 8th grade physics and see what we come up with.
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8 Responses to “Do Larger Tires Get Better Gas Mileage?”
- Glory (17 comments.) on September 9th, 2008 4:24 am
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The First Creditor (32 comments.) on
September 9th, 2008 7:20 am
I can’t really say from a sound physics point of view, however the first thing that comes to mind is that the larger wheel will weigh more, and yield worse gas mileage.
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John (10 comments.) on
September 9th, 2008 4:48 pm
As any good cyclist will recognize, the most important things to worry about when reducing weight and increasing efficiency are the parts of the bike that spin. Very light tires that are inflated to the maximum create the greatest efficiency for the cyclist. I’m sure it applies the same to vehicle gas mileage as well - so I guess I agree with The First Creditor that heavier wheels are not good for gas mileage.
An interesting variant (and maybe this was the original question) is: if you have two tires with the same mass where one has a larger diameter than the other - which one, if any, provides better gas mileage?
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KirkRoy on
September 9th, 2008 6:48 pm
I’m no physicist or engineer… The weight issue (unsprung weight) may depend on type of driving. For constant speed/highway driving the flywheel effect of a heavier wheel may be beneficial (same goes for cycling as well). For stop and go, where you must accelerate from a stop or from low speed, lighter wheels ought to do better (also applies to cycling).
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The Happy Rock (329 comments.) on
September 9th, 2008 11:16 pm
What about diameter of the wheel like John said. One revolution of a larger tire will take you further than smaller tire.
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Bill (4 comments.) on
September 10th, 2008 1:42 pm
All other things equal, larger rolling radius (i.e., bigger wheels and tires) equals better gas mileage. But it may be very insignificant.
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Michael on
December 11th, 2008 11:05 am
It won’t really matter. At highway speeds the fuel economy of a vehicle is dictated by wind resistance alone (the terms regarding this in the governing fluid mechanics equations are non-linear and increase rapidly). At low speeds the fuel economy is dictated by numerous things, including the friction of bearings & pistons in the engine, friction between gears in the transmission, friction in the differential gears, friction between the tires and the pavement, and probably many others. The force required to push a vehicle down the road comes from the torque from the engine. Torque is force*leaver arm, so to get the same force with an increased leaver arm (i.e. increased tire radius) would require an increase in torque. That requires a higher RPM, and probably a higher fuel consumption rate.
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The Happy Rock (329 comments.) on
December 11th, 2008 9:19 pm
@Michael - Thanks for the comment loaded with info.
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I am not quite sure but I think the do. Does anybody know for sure??/