Crash Bytes (June '07)

Avoiding Rollover After Tire Failure

In the hot summer months here in the Southwest we see a big increase in the number of tire failure investigation assignments. Extreme heat will expose inherent weakness in a tire, leading to premature failure. And the large quantity of tread pieces that can be seen lying by the roadside attest to the many tire failures that do occur. So, is it inevitable that a tire failure leads to a catastrophic accident? Obviously not! Lots of failures occur without incident. It is when a vehicle is traveling at relatively high speed (50-60+ mph) and one of the rear tires goes, that disaster can strike.

Extensive studies have shown that a sudden loss of inflation in a front tire does not significantly alter a vehicle's stability. The brakes can be applied and steering control maintained without much difficulty. The same studies have shown that loss of a rear tire will not significantly affect a vehicle's stability as long as the brakes are not applied. However, when a rear tire blows, vehicle stability can be dramatically affected if the brakes are applied suddenly.

Because hard braking causes a sudden weight transfer to the front wheels, if there is uneven traction in the rear (one tire is inflated, the other is not) the vehicle will begin to rotate. At this point, the typical driver will turn the steering wheel to correct the rotation, but may turn the wheel in the wrong direction, or may overcorrect, causing the vehicle to either turn sideways in the roadway, or to drive off the roadway. The result is usually a single-vehicle rollover accident.

The solution, though, is very simple. If you experience a blow-out or sudden tread separation while driving -- DO NOT APPLY THE BRAKES! To maintain control, simply take your foot off the accelerator, allow the vehicle to coast, and begin moving toward the side of the roadway. When your speed has decreased to under 40 mph, you will be able to apply the brakes and safely stop the vehicle without losing control.