South African motorists can save R7,2-billion in fuel costs simply by maintaining the correct tyre pressure on their vehicles.
According to the Automobile Association of South Africa (AA), as well as tyre manufactures, a decrease in tyre pressure rapidly increases fuel consumption.
The United States Department of Energy recommends that fuel efficiency can be improved by 3,3% simply by maintaining the correct tyre pressure.
This titbit of information has even led to an argument in the US presidential race, after Democratic presidential candidate Barack Obama asserted that Americans need to correctly inflate their tyres to ensure the country saves on 3% to 4% its fuel bill.
US conservatives, however laid into Obama’s ”energy plan” for the country.
Time magazine reported that the Republicans had ”a field day” mocking Obama, and that the Republican national committee, the national leadership of the Republican Party in the US, sent tyre gauges labelled ”Barack Obama’s Energy Plan” to Washington reporters.
But it appears Obama is right. A well-serviced vehicle, with tyres inflated to the correct pressure, can save motorists fuel.
Indeed Obama’s Republican opponent John McCain eventually backed down from the debate. Early last week, he reportedly came out saying that ”—Senator Obama — said that we ought to all inflate our tyres, and I don’t disagree with that.”
”Increase in fuel use attributable to tyre pressure can be substantial,” says AA spokesperson Rob Handfield-Jones.
”The correct tyre pressure gives a balance between rolling resistance, traction and keeping the tyre firmly mounted on the rim,” said Handfield-Jones. ”The moment tyre pressure drops, rolling resistance increases, which is bad for fuel Âconsumption.”
With these figures in mind and if enough motorists pay attention, a country could reduce fuel consumption, or in South Africa’s case, save as much as 3% of its fuel usage.
According to the South African Petroleum Industry Association, the country consumed 11,5-billion litres of petrol and 9,7-billion litres of diesel last year. At R10 a litre this brings our fuel bill to R220-billion.
Theoretically local drivers could save themselves at least R7,2-billion by keeping their tyre pressure correct.
This figure could be inflated however since diesel is not consumed through vehicle usage alone. In addition diesel demand has increased owing to Eskom’s use of diesel powered open-cycle turbines, which generate electricity during peak demand.
Fuel efficiency decreases dramatically with the level of pressure in your tyres, says Rodney Idris, manager for commercial tyres at Continental. The recommended tyre pressure by manufacturers has been ascertained through extensive testing, including fuel economy, he says.
”If you car’s recommended tyre pressure is 2 bar and you fill your tyres to 1,4, a difference of 60 kilopascals in pressure, you lose 4% fuel efficiency,” says Idris.
He also says it is very important to check tyre pressure when tyres are cold. Tyre pressures increase as tyres heat up. This can, says Idris, substantially change the reading on your tyres and you waste fuel once you are back on the road.
”Wear also increases as pressure decreases,” he says.
If people take care of their tyres properly, they last longer. Given that tyres use oil in their manufacture, less wear on tyres could, in theory, save us further oil, argues Idris.
According to Handfield-Jones, a European test found that reducing tyre pressures by 12% caused fuel consumption to increase by 8% in heavy vehicles. But he said light vehicles ”are equally susceptible”.
Additionally, properly inflated tyres are safer.
Handfield-Jones says that while over-inflated tyres are not ideal — there is less traction and the middle of the tyre wears faster — under-inflation, is a ”big problem”.
”Apart from wearing rapidly on the shoulders, an under-inflated tyre eventually overheats during driving,” he said.
”This can cause the plies [the various layers bonded together to form the tyre] to separate from one-another, leading to tyre failure. Also, under-inflated tyres reduce traction and steering control noticeably.
”Another risk is that if a driver has to swerve to avoid an obstacle, the lateral forces placed on an under-inflated tyre can dismount it from the rim, or cause the tyre to flex enough so that the rim touches the road surface — this can result in a rollover,” said Handfield-Jones.
The AA recommends that drivers check their tyre pressure once a week.
