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Difficulty: MediumTire Failure and Blowouts

During a terminal safety evaluation, a driver is asked to explain the primary cause of rapid tire failure on the highway and the required emergency procedure if a blowout occurs. Which of the following correctly identifies the main cause of tire blowouts and the proper handling technique?

  1. A
    Overinflation causing rapid tread separation; the driver must immediately apply maximum service brake pedal pressure to bring the vehicle to a complete stop before rim damage occurs.
  2. Underinflation causing excessive heat buildup; the driver must stay completely off the service brake, maintain directional control until speed drops naturally, and then brake gently after moving onto the shoulder.Answer
  3. C
    Operating steer tires with 3/32 inch of tread; the driver should immediately activate the trailer hand brake to stretch the combination unit while steering toward the shoulder.
  4. D
    Mismatched tire sizes on a dual assembly; the driver must immediately apply heavy, pulsed service braking while countersteering sharply away from the side of the failed tire.

Answer

Underinflation causing excessive heat buildup is the primary cause of blowouts; the proper emergency response is to stay off the brake, maintain directional control, allow the vehicle to coast down, and brake gently once slowed.
Underinflation causes excessive tire flexing and internal heat buildup, which is the leading cause of sudden tire blowouts. When a blowout occurs, the driver must resist the instinct to brake, keep the steering wheel steady, allow the vehicle to coast down naturally to avoid wheel lockup or skids, and apply gentle braking only after the vehicle has slowed safely.

Step-by-Step Solution

1
Identify the primary mechanical cause of catastrophic tire failure on commercial vehicles.
Underinflation causes excessive sidewall flexing and rapid internal heat buildup, which weakens tire materials and causes blowouts.
Understanding that heat generated by underinflation is the leading cause of blowouts is essential for preventive inspection and road safety.
2
Determine the proper driver control response during an active blowout emergency.
The driver must hold the steering wheel firmly straight and stay off the service brake pedal entirely.
Braking immediately when a tire fails can cause wheel lockup, loss of lateral traction, and a severe skid or jackknife.
3
Execute the final safe stopping procedure once the vehicle has slowed down.
Allow the vehicle to coast down, check traffic, steer smoothly onto the shoulder, and apply gentle braking to come to a complete stop.
Gradual deceleration and smooth maneuvering onto the shoulder prevent vehicle rollover and ensure safe clearance from active traffic lanes.

Key Concept

Tire blowout causes and emergency coast-down control procedures
Estimated Time:1m 0s
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Topics

Tire Failure and Blowouts

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