As petrol prices continue to rise across the country, many people are desperate for ways to save money on petrol. Over the years, motorists, mechanics and other car enthusiasts have come up with a number of methods of purportedly improving a car’s fuel efficiency.
Some people claim mileage gains by running their tire pressure above the manufacturer’s recommendations. In theory, that makes sense: With more inflation pressure, the tire bulges in the centre of the tread and creates a smaller, skinnier contact patch with the road. This should mean less rolling resistance and increased mileage.
U.S. Department of Energy says that for every five pounds per square inch (psi) of tire pressure you lose can translate into a two percent loss of fuel mileage. You can usually find your recommended pressure on the inside of the driver’s side door or your car owner’s manual. Some models even place the stickers on the trunk lid, in the console or on the fuel door.
If under-inflated tires drop your fuel economy, then over-inflated tires must give that mileage a boost. Could this be right?
Here is the truth behind one of the most popular fuel-saving myths:
Over-inflate your tires
Myth: Keeping tires inflated above their recommended pressure will help maintain a car’s optimum fuel consumption.
You may think that over-inflating your tires would save money on gas.
In 2009, Popular Mechanics tested this premise by over-inflating the tires on a Honda Fit to 45 psi (13 psi above the recommended pressure). On a drive from Los Angeles to Phoenix, the magazine’s writers recorded a fuel consumption of 42.19 miles per gallon (5.575 litres per 100 kilometres).
On the return trip, they dropped the pressure back to the recommended 32 psi, and the car’s fuel consumption was nearly identical, at 42.14 mpg (5.581 L/100 km).
They noted that driving with over-inflated tires greatly reduced the car’s handling and made for a bumpier ride. If you over-inflate your tires too much, the vehicle’s handling is compromised and you will be at risk.