Does over inflating a cars tires help increase fuel economy? Yes but... the dangers outweigh the slight benefit. It is true that one of the top ways to gets the best possible fuel economy from your car is to maintain proper tire pressure. Underinflated tires will cause drag, under performance and uneven wear and reduced fuel economy. So it may sound like over inflating would cause the opposite, the truth is that it will only slightly help and comes with the increased risk of a blowout. You will also reduce the traction, handling and braking performance. The best thing to do is check your car's tire pressure regularly. Most modern vehicles come with automatic low pressure warnings, this may full you into thinking that unless there is a warning that your car is at proper inflation. Most vehicle tire monitoring systems are designed to warn you only when the air pressure reaches the bottom threshold which could mean that you have been driving at sub-optimal levels for quite some time. Better to check them manually once a week. You may also discover that one tire has a slow leak if you find that one of them is constantly lower that the others. Another benefit is that you will routinely be getting "up close and personal" with your car's tires on a regular basis. You may encounter a damaged car tire or bent rim that you otherwise wouldn't have know of. This can save you from getting stranded on the side of the road or even worse.., a car accident. There's no downside, check regular.