Updated on 07.29.14

Five Minute Finances #7: Air Up Your Tires

Trent Hamm

Five Minute FinancesFive Minute Finances is a series of tips on how you can save significant money or reorganize your financial life in just five minutes. These tips appear Monday, Wednesday, and Friday on The Simple Dollar.

According to CarCare.org, underinflated tires can reduce gas mileage by 0.4% for every 1 PSI below the recommended maximum in all four tires. Even more amazing, a car tire can be 10 PSI or more under this recommended maximum and not appear low at all with visual inspection, reducing your gas mileage by 4%. Over a year, keeping your tires properly inflated can save $40 even on a car with good gas mileage (10,000 miles driven in a 20 MPG car with gas costing $2 per gallon). If you drive more, or your auto gets worse mileage, you can save substantially more.

Even better, keeping your tires at the proper inflation reduces wear on your tires, thus extending their life, and also reduces the risk of a blowout. Though this savings is a bit more intangible, it will save you money over the long run.

The procedure for airing up your tires is very easy and can be done for free at most gas stations. The only thing you’ll need is an air gauge, which you can borrow from the front counter at many stations (though I found it easier to just start keeping one in my own glove box). Here’s what you do:

1. Look inside the door jamb of your car for a sticker. It should tell you the recommended maximum pressure for tires on your automobile.

2. Let the tires cool before checking their pressure. In other words, if you go to the station to do this, go to one near your home shortly after starting to drive after letting your automobile sit overnight.

3. Remove the cap from the valve on one tire. The valve is pretty obvious – it sticks out and has a little cap on the end that you can easily twist off. Put the cap somewhere where you won’t lose it (I lost one the first time I did it).

4. Push the tire gauge hard onto the valve. If you hear hissing, pull it off and try again, because that means you’re leaking air. You want to line them up straight and push firmly.

5. Add air to the tire. Take the air hose, press it onto the valve in much the same way as the gauge, and push about half a second for each PSI your tire was under the recommended maximum. Check the pressure again and add more if you need to using this rule of thumb.

6. Replace the valve cap.

7. Repeat steps three through six for all of your car tires.

You can also use this opportunity to check the wear on your tire. Jam a penny with the head out into the tread; if you can see any of Lincoln’s head, you might want to think about getting new tires.

How often should I do this? You should do it monthly during warm months and maybe once every two weeks in cold weather. I do it about every other fill up in the winter and about every third or fourth one in the summer.

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  1. palemelanesian says:

    When you do this, be sure to also check the spare. There’s nothing worse than having a flat and finding out your spare is also flat.

  2. wop9 says:

    I’m not so sure the measurement you’re using to check tire wear is correct. You say:

    “if you can see any of Lincoln’s head, you might want to think about getting new tires.”

    I think the rule is if you can see the top of his head, then you need to get new tires.

  3. Ed says:

    You can overinflate 2 to 4 pounds and get a bit better mileage. Also, I generally go by the pressure printed on the tires rather than the manufacturer’s suggestion. The car companies have the tires a little soft for a smoother ride. Of course, I could be wrong.

  4. Baz L says:

    When filling up I usually remove ALL the caps when adding air and replace all after I’m done. Why? Because we have a lot of those pay-for-air gas stations. There’s nothing worse than having your 50 cents run out while you’re unscrewing the last cap on the last tire.

  5. Danielle says:

    Our local gas stations don’t offer free air, but my in-laws got us a car emergency kit that we use for road trips that has a little electric air pump. It’s completely worth whatever they paid for the whole kit, and there are other useful things in it.

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