In 1995, the DOE did a study that showed that under-inflated tires in American cars waste 15 million litres of gasoline a day, or about 5.6 billion litres a year.
At 75 cents a litre, that's about $4.2 billion a year in unnecessary fuel costs. If the tires in your vehicle are a lot softer than they're supposed to be, you could actually be spending a bigger percentage on gasoline than that and that could translate into a lot of money.
Other findings of note from the RMA study include:
''Underinflated tires cause excessive heat buildup and heat is the enemy of a tire,'' Shea said. ''Over time, this can cause internal damage that may lead to tire failure.''