How Checking Your Tire Pressure Every 2 Weeks Saves You Money

by mzumtaylor on November 20, 2010

in Advice

I’ve always been told that if my car tires are properly inflated, my car will get better gas mileage, but I never really got why.

I suppose if I had sat down to think about it, I could have come up with something resembling the answer: Having lower tire pressure increases the amount of contact your tires have with the road, which increases friction and slows down your car.

But knowing that, and doing something about it are two different things.

Then I got a personal experience lesson in exactly why having properly inflated tires can save you money and improve your gas mileage.

The situation

I ride my bike to work as much as possible, because I live less than a mile from work, and I’d rather bike than put the wear and tear on my car. (It takes longer to warm my car up properly than it does to drive over there.)

Usually when I ride over there, there’s one flat stretch where I put my bike in the highest gear setting (biggest gear in the front, smaller gear in the back — requires more effort to pedal) because everything else is too easy and doesn’t get me very far very fast.

Then, the other day, I was going up that stretch and putting my bike in the highest gear setting was just freaking hard. I shifted down to the middle gear setting, and even that took a lot more effort than usual.

What Happened

When I got home, I went to check my tires and they were a little soft, so I decided to pump them up. As soon as I attached the pump to the tires I could see the problem: my tires were both at 20 psi, where they’re supposed to be between 40 and 60 psi.

Because my tires on my bike were under-inflated, my effective “mpg” (or in this case FPE, or “feet per effort (exerted)”) dropped significantly. It was in that moment that I finally got it, in a purely physical way, why having your tires on your car properly inflated makes such a difference.

The Point

Everyone will tell you to keep your car tires properly inflated, but if that’s not motivation enough to check the pressure in your tires every two weeks, deflate your bike tires and go for a short ride, and then try the same ride again with them properly inflated. You’ll see what I mean, and chances are good that you’ll check your car tires regularly. I know I have been.

And if you need even a little more incentive, checking your tires will save you money in gas by keeping the miles per gallon of your car up as high as it can be, and that’s never a bad thing.

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Abigail December 22, 2010 at 9:13 am

This is a great reminder for everyone – I’ve heard some astonishing figures about just how much gasoline would be saved each year if Americans just kept their tires properly inflated, and it’s pretty horrifying (and no, I don’t remember the figures right now). It seems to me, since petroleum is something that we seem to be ready to go to war over, that we should be willing to keep our tires inflated to preserve it.

When I first started driving, my mechanic, who happens to be not only one of my mother’s best friends but a total genius and one of America’s most “green” mechanics, told me to do two things every other time that I gas up: check my tire pressure and my oil. He said that doing these two minor things, which can be done while your tank is filling up, can save you hundreds of dollars in gas over the years, and can save your engine from tons of expensive wear and tear. I once had an engine blow on me because of running with no oil – I had a slow leak I didn’t notice because I never checked my oil. That was $4500 to rebuild my engine which could have been avoided by taking 30 secs to check. Lesson learned.

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