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Difficulty: MediumTyre Safety and Requirements

While driving on a level road, you notice that the steering feels unusually heavy and sluggish when turning. Which tyre defect or condition is the most likely cause of this issue?

  1. The front tyres are significantly under-inflatedAnswer
  2. B
    The front tyres are inflated above the recommended pressure
  3. C
    The front tyres have worn below the legal minimum tread depth of 1.6 mm1.6\text{ mm}
  4. D
    The tyre pressures were set when the tyres were completely cold

Answer

The front tyres are significantly under-inflated.
When front tyres are under-inflated, the tyre carcass flexes and a larger surface area remains in contact with the road. This substantially increases rolling resistance and friction, requiring noticeably greater effort from the driver (or steering system) to turn the wheels.

Step-by-Step Solution

1
Identify the reported vehicle handling symptom
The driver experiences heavy, sluggish steering during turns on a level road surface.
Vehicle handling symptoms directly correspond to specific mechanical and pneumatic tyre conditions.
2
Evaluate the mechanical effects of incorrect tyre pressures
Low tyre pressure allows the tyre sidewalls to flex excessively, increasing rolling resistance and the surface contact area, which requires greater effort to turn the wheels.
Under-inflation increases frictional resistance at the steering axle, whereas over-inflation reduces the contact patch.
3
Select the condition matching the heavy steering symptom
Under-inflated front tyres are the direct cause of heavy steering.
Neither illegal tread depth nor standard cold-pressure adjustment causes increased steering resistance.

Key Concept

Tyre Pressure Effects on Vehicle Handling and Safety
Estimated Time:50s
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Topics

Tyre Safety and Requirements

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