ask Straight Dope; Cecil

 

Dear Cecil:

I have a theory that, as a nation, we could save about 10 per cent of
our gasoline consumption by the simple expedient of making sure our
tires are fully inflated. My questions are: (1) What is the relationship
between underinflation and gas mileage deterioration (e.g., 20 percent
underinflation reduces mileage 10 percent, etc.)? (2) What is the
trade-off between tire inflation and tire life? (3) Do the auto
manufacturers in fact specify too low an inflation level for tires in
order to soften the ride?

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