Underinflated Tires

posted: 04/11/12
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As seen in "MythBusters: Minimyth Madness"


Explanation: Per a viewer request, MythBusters Kari Byron and Grant Imahara let the air out of a set of car tires to see if it would have any effect on gas mileage. A common green driving tip says keeping your tires properly inflated should help maximize mileage, but does it really make a difference at the pump? And what happens if you're driving on too much air?

Kari and Grant drove around a course and tracked how much gas they burned while motoring with the proper tire pressure, as well as with over- and underinflated tires. Cruising with tires that were 15 percent underinflated, their car guzzled 1.2 percent more fuel. And with tires 15 percent too pumped up, the car used 6.2 percent less fuel, since there was less surface area of rubber meeting the road.

However, the cost savings of driving on overinflated tires worked out to only around $76 per year, which is much less than the potential expense of a tire blowout.

To go green and save money safely, the MythBusters confirmed the standard tire recommendation is right: Stick with the proper tire pressure.

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