Under-inflated tires use more fuel

Our poor tires appear to be the least likeable aspect of motoring.

By Wheels Wheels.ca

Apr 21, 2007 4 min. read

Article was updated 17 years ago

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Our poor tires appear to be the least likeable aspect of motoring.

Consumers hate the fact that tires wear out and are expensive to replace. They are a grudge purchase. And once the price is mentioned, it becomes an even bigger grudge.

Tires do not get any respect. We drive them over curbs, we make them jump through potholes, over miscellaneous debris, and worst of all, never check their air pressure.

And that all costs money, a lot of money, money coming out of the driver's pocket. But the financial penalty is not the worst of it: lack of respect for your tires is causing you to use far more fuel than necessary.

It is a well-known fact that under-inflated tires cause a loss of fuel economy and accelerate tire wear. In plain words, low tire pressure means you use more gas and ruin more tires. Under-inflation of the tire by 10 per cent increases the tire's wear rate by 5 per cent and increases gas consumption by 2 per cent. Twenty per cent under-inflation increases tire wear by 16 per cent and increases gas consumption by 4 per cent. Take low pressures to an extreme of 40 per cent below factory specs and you increase the tire's wear rate by 57 per cent and fuel consumption by 8 per cent.

The Rubber Association of Canada (RAC) website tells us that "every litre of fuel consumed by a vehicle results in 2.4 kg of carbon dioxide, a greenhouse gas that contributes to climate change, being released into the environment.

"Proper tire inflation helps increase fuel efficiency thereby reducing greenhouse gas emissions. Every year in Canada, 1.5 million tonnes of carbon dioxide are unnecessarily released into the environment because of poor tire maintenance practices."

This statistic is especially alarming since a study by the Rubber Association and the federal government produced some truly scary statistics about tire inflation practices in this country.

In a cross-country survey, the study found that 70 per cent of vehicles randomly tested had at least one tire with an inflation problem. Seventeen per cent of vehicles had a tire over-inflated by at least 20 per cent. And 23 per cent of vehicles had at least one tire under-inflated by more than 20 per cent. That kind of under-inflation results in using about two weeks' worth of extra gas per year and reducing the tire's life by nine months, all the while pumping out unnecessary carbon dioxide.

The study concludes improper inflation costs each Canadian $500 per year and causes an extra 1.5 million tonnes of carbon dioxide to be released. If the financial argument is not enough, consider that under-inflation is the number one cause of tire failure. An under-inflated tire gets hotter faster and heat leads to tire blowouts.

The survey tells us three out of four people wash their car every month, but only one in seven checks tire pressures: a measly 14 per cent of us care about our safety and the environment.

Considering tires under normal use can lose about 1 p.s.i. per month and more if driven on rough roads, we should break out that pressure gauge and see what's happening where the rubber meets the road.

And don't just use your eyeball; a modern radial that is inflated to 30 p.s.i. will not show any significant changes in the sidewall until it is down to the 22 p.s.i. range.

Check your tire pressures at least once a month and make sure they match the vehicle manufacturer's specs found in the owner's manual or the vehicle placard inside the door jambs or gas tank flap.

Remember to check the air pressure in your spare, too.

Do not inflate the tires to the maximum pressure indicated on the sidewall, unless you are loading the vehicle to its maximum capacity. Remember to let some air out after the car gets back to its normal load.

Disposing of old tires also has an impact on the environment. Canadians discard 28 million used tires every year, many of which end up in landfills or recycling centres. Every effort made to reduce the number of used tires will lead to a reduction in the amount of gasoline and other types of energy required to transport, dispose of or recycle them.

By better maintaining our tires, we could prevent emissions of carbon dioxide (CO2) and other pollutants from entering the atmosphere.



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