Consequences of Over or Under-Inflated Tires

by Justin Cupler

Automotive tires rage greatly in PSI capacity, with anywhere from 34 PSI all the way up to 90 PSI. The vehicle manufacturers also have their own recommendations; this is the rating that should always be followed. The maximum inflation on the sidewall of a tire is just for reference, not a recommendation. There are consequences, some severe, for not following the vehicle manufacturer's specified tire PSI.

Blow-out

Blow-outs are the catastrophic failure of a tire. The internal bands completely fail and the tire then explodes. While exceeding the manufacturer's recommendation may seem OK since you are still within the tire's range, it can still cause issues. The manufacturer recommends this PSI to compensate for hitting large bumps. Heavy impacts compress the air in the tire, causing momentary spikes in the PSI. This quick spike can cause a blow-out if the tire is too close to its maximum rating. Under-inflation can cause a blow-out as well. When a tire is under-inflated, the sidewall bulges outward. This additional flex in the sidewall compromises its ability to bear weight and can cause the sidewall a blow-out.

Fuel Economy

Under-inflated tires can greatly impact the fuel economy of your vehicle. The lower the tire pressure, the greater the rolling resistance of that tire. The greater rolling resistance requires more work by the engine to move the vehicle, lowering fuel economy.

Handling

Under-inflation can greatly impact the handling characteristics of your vehicle. Under-inflation allows the sidewall to become flexible. This causes a lot of movement of the vehicle relative to the tread and can lead to the tread losing contact due to abrupt movement of the vehicle.

Tread Wear

It is a common goal among most drivers to get the maximum life out of their tires. Over- and under-inflation can significantly decrease the life of your tires. Over-inflation causes the center section of the tread to balloon outward. This puts more weight on the center of the tire. This extra weight causes the center of the tire wears quickly. Under-inflation does the opposite--it allows the center to cave inward, forcing the outer edges to bear more weight. This extra weight leads to inner and outer edge wear.

Comfort

Over-inflated tires impact the ride comfort of your vehicle. Over-inflated tires cannot absorb the impact of small holes in the road as well as properly inflated tires; this causes a bumpy ride. Due to the harder sidewall, the tires also transfer much more road noise into the cabin of the vehicle.

Hydroplaning

Hydroplaning is when the tires contact with the road is broken by a layer of water. This causes a temporary loss of control of the vehicle. Under-inflation increases the chances of hydroplaning as it creates a larger footprint. This larger footprint allows more water to get in between the tire and the road thereby causing hydroplaning.

About the Author

Justin Cupler is a professional writer who has been published on several websites including CarsDirect and Autos.com. Cupler has worked in the professional automotive repair field as a technician and a manager since 2000. He has a certificate in broadcast journalism from the Connecticut School of Broadcasting. Cupler is currently studying mechanical engineering at Saint Petersburg College.

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  • photo_camera stack of old tires image by JoLin from Fotolia.com