Boyd's Blog

Driving around on underinflated tires is just a bad idea all the way around. Underinflated tires increase a car’s rolling resistance, meaning a drop in fuel efficiency since it takes more energy to move the vehicle down the road.

A single tire that’s down by ten pounds of air means a 3.3 percent drop in fuel economy…multiply that by all four tires, and you can figure on giving up ten percent of your gas mileage. The added friction and rolling resistance also means more heat is generated, and heat is the enemy of the internal structure of a tire. That heat will damage a tire to the point of failure. Studies show that underinflated tires are a full 25 percent more likely to fail, and at least half of one-car accidents involve a tire problem as a factor. And still, it’s estimated that 60 to 80 percent of the vehicles on the road are rolling on tires that are low on air.

The tire pressure monitoring systems on newer cars are all well and good, but what can be done to stabilize tire pressure in vehicles, especially when many drivers just ignore it?

Self-inflating tires are on the horizon. For military vehicles and heavy trucks, self-inflating tires have been around for a while, but they always involved a compressor or air reservoir on the vehicle to supply air. There are now a couple of new, innovative designs for self-inflating tires:

• A system from SIT uses a tube chamber near the bead of the tire wall. At its lowest point, the tube is kept closed with the normal deformation of a tire due to the weight of the vehicle. The portion that’s squeezed closed constantly changes as the tire rolls. If the tire pressure drops, sensors and an automatic pressure regulator kick in and the squeezing/releasing action of the tube begins to suck in atmospheric air. When the tire reaches its proper pressure again, a check valve prevents the tube from introducing any more air. The SIT design actually won the 2009 Tire Technology of the Year award at the Tire Technology Expo.
   
•  A system designed by Halo uses a pendulum-type mass that’s suspended at the center of the truck wheel. As the wheel rolls, the pendulum swings and drives a self-contained pump which adds air until the desired air pressure is reached. This five-pound unit mounts directly to the wheel’s axle cap, not unlike a hub odometer. While it’s currently only available for heavy trucks, buses and tractor-trailers, the Halo system has been tested for over 8 million miles on various vehicles.

While these self-inflation designs may not be widely used yet, they point the way to a time when having to worry about tire inflation will be a thing of the past. What kind of shape are your tires in? Have you checked their inflation level lately? Give us a call and make an appointment at the shop and let us have a look at your tires!