I enjoy reading these on occasion since you signed me up for the SafetyXChange list a year or two ago. This morning I noticed a safety tip in the first article that was not quite up to par:

Tip 2: Pump Up the Tires

It's a common misconception that keeping less air in tires improves traction in hot weather, on snow or when you're carrying a heavy load. In fact, the opposite is true. Under-inflated tires are much more likely to blow out, come off the rims or "hydroplane" on wet roadways. For better handling and mileage, you should inflate tires to the maximum air pressure recommended by the manufacturer.

The statement that one should "inflate tires to the maximum air pressure recommended by the manufacturer" is a common misconception and entirely wrong! Rather, one should inflate tires to the air pressure recommended by the vehicle manufacturer as shown in the vehicle's owner's manual and a decal, which is often located on the side of the driver's door. The maximum air pressure shown on the tire itself is the maximum pressure recommended by the tire manufacturer. Though in some cases this value may be equal to that recommended by the vehicle manufacturer, this number is shown on the tire as a maximum limit to prevent unsafe inflation beyond the tire's design; a value which is dependent entirely upon the tire, with no consideration toward application.

The air pressure shown on the vehicle's decal & manual is the vehicle manufacturer's recommendation which is developed with consideration to not only the design tire, but the vehicle's weight/geometry. Keep in mind that a given tire may be applied to several different vehicles of various weight and handling characteristics. Were one to inflate a tire based solely on the tire manufacturer's maximum pressure, in most cases a lighter vehicle would experience reduced traction and increased wear along the center of the tire.

Lee E. Edgar
Civil Engineer I

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