At the turn of the 21st century, the National Highway Traffic Safety Administration (NHTSA) conducted a study of nearly 12,000 vehicles to check the status of their tire inflation. The study revealed that almost 40 percent of the vehicles tested had at least one if not more of their tires underinflated by as much as 20 percent.
Furthermore, nearly 30 percent of the tested vehicles were operating with tires under-inflated by 25 percent or more. But the figure showing on the tire only reflects the maximum pressure the tire should reach, not the recommended pressure to which it should be inflated.
Busting the myth of recommended tire pressure
Why is this an issue? It all stems from the Firestone recall of 6.5 million tires after a series of accidents occurred as the result of poor tire construction. The “smoking gun” to blame for the tire failure leading to the rash of accidents was low tire pressure.
According to Best Tire Review, the pressure stamped on the tire sidewall shouldn’t be the actual pressure in the tire.
The effects of friction on tire pressure dynamics
As you drive your car, the movement of the tire on the road creates friction. Friction generates heat. Heat causes the tire pressure to increase.
If the interior tire pressure is filled to its maximum before this reaction occurs, it’s easy to see the potential for a tire to exceed its recommended maximum pressure. This makes for an unyielding ride, where the bumps in the road are more jarring on passengers and the vehicle suspension.
It reduces the footprint of contact on the road that causes uneven wear toward the center of the tire. Don’t let the sensation of steering response and cornering stability give you the false impression that overinflation is safer. Your tires will be more susceptible to puncture or blow-out while you’re driving.
The hidden dangers of under-inflated tires
There really is a bit of the Goldilocks scenario about determining the correct tire pressure. If they have too much pressure, they don’t grip; too low, and they can fail.
Low pressure absorbs more of the impact on the road. This can create improper flexing of the side wall and reduce roll resistance, not to mention the excess wear and tear on suspension. The effect can be overheating of the tire, which can lead to tire separation or blow-out.
Tire pressure monitoring
Vehicles that are 2008 models or newer will have a tire pressure monitoring system (TPMS) built in. This is the result of the TREAD Act enacted by Congress in 2000 as a result of the failures.
The system performs by sensing the tire pressure either directly or indirectly, which means the warning light on the dashboard either indicates the actual pressure or simply reports a potential underinflation of any one of the four operating tires.
As helpful as this system may be, it can still lull drivers into a false sense of security, and encourage them to fail to check the pressure in a timely fashion. Nothing beats having a reliable tire pressure gauge that may be used to check on the true tire pressure reading while the vehicle is cool.
This is when it should be at the recommended pressure, which is typically found on the inside of the driver’s door, glove box, or owner’s manual.