Benefits of Proper Tire Inflation
Safety
In order for your tires to do their job correctly, they need to be properly inflated. Under- or over-inflated tires can lead to tire failure. It is important for the safety of you and your family (other drivers, bicyclists and pedestrians too) to check your tires once a month. Improperly inflated tires can cause your vehicle to experience the following handling problems:
- Trouble with acceleration
- Hindrance with the ability to brake and steer properly
- Interference with the antilock brake, traction control, and stability control systems
Cost 
Under-inflated tires tend to flex more because of the pressure exerted by your car. The extra “flex” of the tire increases rolling resistance, which can cause uneven wear and lower MPG. Tires lacking proper inflation:
- Reduce fuel efficiency and may use up to an extra 144 gallons of fuel per year
- Have shorter life expectancies, causing drivers to purchase new tires more frequently
- Get punctures more often, increasing tire maintenance expenses
- Can cause a blow-out or vehicular accident which can lead to expensive repairs, replacements and insurance
Properly inflated tires helps your vehicle run more efficiently and safely, reduces tire maintenance costs and may save you $400 per year!
Environment
Air Pollution
Incorrect tire pressure leads to decreased gas mileage, increased fuel usage and more pollution in the atmosphere from burning extra fossil fuels to power our vehicles. Air pollutants emitted from motor vehicles include particulate matter, hydrocarbons, volatile organic compounds, nitrogen oxides, and carbon monoxide. These pollutants are harmful to human health and the environment.
Greenhouse Gases
Carbon dioxide (CO2) is also emitted as fossil fuels are burned in vehicles. CO2 is a greenhouse gas which traps heat in the atmosphere. For every tank of gas consumed (~12 gallons) about 240 pounds of CO2 is produced. [How does a gallon of gas weighing only 6 pounds produce about 20 pounds of CO2? Well, when fossil fuels are burned, the hydrocarbons break apart into hydrogen and carbon and recombine with air. The hydrogen molecules bind with oxygen to form water, and carbon molecules combine with oxygen to form CO2. The weight of the oxygen from the air is added to the weight of the carbon from gasoline. The weight of CO2 is about three times heavier than the molecule of the original gasoline.]
Disposal Issues
The disposal of used tires also poses a problem to the environment. Hundreds of thousands of waste tires end up discarded each year in Pima County alone. By properly inflating your tires, you can help reduce the number of discarded tires and the subsequent energy needed to dispose of or recycle them. The Waste Tire Collection Facility in Pima County receives about 73,000 tires every month! These tires are shipped to the Phoenix area where they are recycled. Old tires can be recycled and turned into:
- Rubberized asphalt
- Sports fields and athletic tracks
- Mulch
- Molded rubber products
Remember, recycling is good, but reducing waste is even better! With monthly tire pressure checks and proper inflation your tires will last much longer which reduces the need for the disposal of old tires and the purchase of new ones. Savings all around!
Important Facts & Tips
Ever ride a bicycle on a flat or low tire? It's a lot of work! It's like that with cars and trucks too. Low tires increase rolling resistance, or drag. Because it takes more energy to keep the vehicle moving, more fuel will be burned, causing more air pollution and greenhouse gases.
- To find the correct tire pressure for your vehicle, do not use the maximum pressure noted on the sidewall of the tire. Instead, use the recommended pressure indicated in the door jamb, glove compartment, fuel door, or owners manual.
- Check inflation pressure when tires are cool.
- Never reduce tire pressure when tires are hot.
- If a tire needs air every time you check, ask a tire shop to inspect it for a slow leak.
- Tires must be replaced when the tread is worn down to 2/32 of an inch or when you see the “wear bars.”
- Tires can be 30 percent underinflated before appearing flat.
- Tire pressure monitoring systems may not warn drivers until tires are up to 25 percent underinflated.
- Tire pressure can vary up or down one to two pounds for every 10 degrees of temperature change.
- U.S. drivers waste two million gallons of gas per day due to under-inflated tires.
- Remember to check the spare and add air as necessary.
- Tire pressure should be checked every month, before out-of-town trips, and when weather changes significantly.
- Soft tires may contribute as much as 1.5 extra tons of greenhouse gases into the environment annually.
- Tires should be rotated every 5,000 to 8,000 miles.
- A National Tire Usage Survey indicates that 80 percent of tire problems in the U.S. are caused by improper tire inflation. Under-inflated tires contribute to more than 600 highway deaths and 33,000 injuries a year.
- Proper tire pressure will conserve approximately 144 gallons of gasoline annually, saving you hundreds of dollars.
- Driving on properly inflated tires will improve your vehicle's ability to handle well and stop quickly.
Tire Inflation 101: Checking & Adjusting Vehicle Tire Pressure
Checking Tire Pressure
- Find the air pressure specifications for your vehicle's tires in the driver's side door jamb, glove compartment, or owner's manual (not on the sidewall of the tire).
- Unscrew the tire's air valve cap from the valve stem. Put it in a safe place so you don't lose it.
- Place the gauge over the tire's valve stem and press firmly so that no air escapes. Check the gauge for the tire pressure.
- Repeat steps 3-4 for each tire (remember the spare tire too) at least 3 times to check the accuracy of the reading.
- Compare the results to the proper psi for your vehicle.
- Add or release air as needed (refer to adjusting tire pressure).
- Replace the valve caps.
Adjusting Tire Pressure
If you find your tires to be under inflated:
- Go to a gas station or garage with pressurized air with a gauge. Pull the car up to the air compressor making sure the hose will be able to reach all four tires.
- Unscrew the plastic caps on the air valves of the tires that need the pressure adjusted. Put caps in a safe place so you don't lose them.
- Turn the air compressor on.
- Firmly press the air pump hose onto the tire valve and squeeze the lever (this will begin air flow).
- Release the lever when the proper psi is shown on the hose gauge and recheck the pressure with your own tire gauge.
- Repeat steps 4-5 for each tire as needed.
- Deflate the tires if you accidentally overfill them.
- Replace the valve caps and you’re ready to drive!
If you find your tires to be over-inflated:
Press down on the small needle in the center of the air valve to let air out. Many tire pressure gauges have a small knob for this purpose, but a nipple on the back side of the tire gauge cap, key, fingernail, or pen would also work.
Program Partners
Thanks to the City of Tucson Office of Conservation and Sustainable Development, Pima Association of Governments Clean Cities Program, and Jack Furrier's Tire and Auto Care for assistance with this Tire Inflation Education Program. Multiple agencies and a local business working together to improve air quality and reduce waste in our community.
