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Top-off The Tires Featured on Nov 12, 2008

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Challenge Details

This challenge was originally published on November 15, 2007.

Ever ride a bike with soft tires, and notice it’s a bit harder to pedal? The same thing happens with your car. It needs to work harder when tire pressure is low. So, give your car, the environment, and your wallet a break by topping-up your tire pressure once a month.

The Carbon Connection
Close to 30% of the greenhouse gases released in the United States come from transportation. Of that amount, over 80% is produced by our vehicles driving on the roads and burning gasoline or diesel. Each gallon of gasoline burned by an average car’s engine releases 19.4 pounds of CO2 into Earth’s atmosphere. Cars on average generate about 990 pounds of CO2 per month.

There are several ways for Rallyers to reduce transportation-related carbon impact. We can drive less and walk more. We can carpool or use mass transit where available. We can buy cars that get more miles per gallon. And we can maintain the cars we already own so that they get the best possible gas mileage.

A simple way to reduce the CO2 impact of a car is to keep the tires filled to the manufacturer’s recommended pressure. It is estimated that over 25% of cars in the United States are driving on under-inflated tires. Cars driving with properly inflated tires are 3.3% more fuel efficient than cars driving on under-inflated tires and therefore emit 3.3% less CO2. Given the amount of gasoline burned by cars and trucks in the United States each day, the simple action of everyone maintaining proper tire pressure would mean a monthly reduction of over 90 million gallons of gas. And that translates to a potential monthly reduction of around 1.8 billion pounds of CO2 released into Earth’s atmosphere.

Getting It Done
Reducing massive amounts of CO2 begins with people taking simple actions such as this one. Here are a few suggestions to help you get it done:

• Maybe you don’t personally own a car. But you ride around in someone else’s car. Make sure the owner of your ride checks their tires this month. For instance, you might say, “Mom? Dad? Have we checked the car’s tires? I don’t want to drive to Grandma’s house for turkey on tires that aren’t properly inflated.” And then, when you explain why you care, maybe they’ll join the Rally too!
• Tires lose air over time. Unless you’re keeping an eye on them, chances are your tires are under-inflated. So you need to learn how to check your tires’ air pressure. It’s simple. You should be able to pick up a tire gauge for between $10 and $20 at your local auto supply shop or online. Owners of 2008 model year cars and light trucks will find their new cars now come with tire pressure sensors and warning lights. If you own one of these cars, you can pass your tire gauge on to the next guy.
• Next, you need to find out the correct air pressure for your car’s tires. You can usually find that information on a sticker on the driver’s side door edge, door frame, or sill.
• It is best to check your tires’ pressure when they are cold. Tires heat up as you drive. Test your tires when they haven’t been driven for at least three hours. And don’t forget to check the spare!
• Don’t under-inflate or over-inflate your tires. This hurts the tires. Driving on tires that aren’t properly inflated shortens their lives and they aren’t cheap. And don’t believe the old wives’ tale about keeping your tires under-inflated in the winter to increase traction. Under-inflated tires are more prone to skidding, hydroplaning, and loss of control from blowouts or flat tires.

Rules of the Challenge
The duration of this challenge is 1 month, and the total CO2 reduction is 29 lbs. So, if you accept this Challenge, you’ll see a about 1 pound of CO2 reduction added to your account each day for the next 30 days.

This Challenge is repeatable. Remember, tire pressure changes over time. So check your tires again next month. If you find your tires have lost some air since the last time you checked, reinflate them to the proper pressure, and accept this Challenge again for an additional month of CO2 credit

Remember, you should only accept Challenges when they motivate you to take a new climate- saving action. If you already check your tires monthly, this challenge isn’t for you. Instead, you can help by finding other people to check their tires and take this Challenge.

Learn More
Check My Tires
Proper Tire Inflation

See the Math
Let’s start with the known or estimated numbers:

• The average American car is driven 12,000 miles each year. That’s an average of 1,000 miles per month.
• The average American car gets 19.6 miles per gallon of gasoline.
• Properly inflated tires result in 3.3% better mileage, raising the average car’s miles per gallon to 20.2.
• Driving a car 1,000 miles a month with the increased gas mileage leads to a savings of 1.5 gallons of gasoline per month.
• Each gallon of gasoline burned by an automobile releases 19.4 pounds of CO2 into the atmosphere.

Now put all that together to get the following equation:

Your numbers may vary. You may drive your car more or less than the national average. Your car may get better or worse mileage. And perhaps your tire pressure was closer to ideal or even much worse than the average level of under-inflation. The important thing to look at here is just how much carbon dioxide gets formed and released each day as you drive your car. At almost 20 pounds of CO2 and $3.00 for every gallon of gas you use, even small increases in your gas mileage result in big savings at the other end of your tailpipe.

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