Under-inflated tires waste gas. Think how hard it is to walk in sand – you just have to work harder because of the resistance. When your tires don’t have enough air in them, their rolling resistance is dramatically increased and it simply takes more gas to get where you’re going.
Always check your tire pressure when you gas up. If they’re low – even just a little bit – bring them up to proper pressure. There’s a sticker on the inside of the driver’s door that gives the manufacturer’s recommended tire pressure.
And don’t rely on your tire pressure monitoring system to alert you to when you need more air. The TPMS system is set to warn you when pressure drops twenty percent below recommendations. That’s severely under inflated and you needed more air a long time ago. And if you have a slow leak – get it fixed right away.
Get some air and save some gas.