Automotive tyres — diagnosing tread wear from inflation level For a passenger vehicle on standard road tyres, an under-inflated tyre typically shows its most pronounced tread wear in which region of the tread?

Introduction / Context:
Tread-wear patterns are a quick diagnostic for tyre health and vehicle setup. Recognizing the characteristic wear caused by incorrect inflation pressure helps improve safety, tyre life, and fuel economy.

Given Data / Assumptions:

• Pneumatic radial tyre on a passenger car.
• Vehicle alignment and suspension components are otherwise serviceable.
• Tyre operated significantly below recommended cold inflation pressure.

Concept / Approach:
Tyre contact patch shape changes with inflation pressure. Under-inflation increases sidewall deflection, letting the shoulders carry a higher share of vertical load and shear stress. This accelerates wear on the outer tread bands (both edges) while the centre carries less load and wears comparatively less.

Step-by-Step Solution:

Verification / Alternative check:
Measure tread depth at three positions across the tyre (inner edge, centre, outer edge). Under-inflated tyres show lower depth at both edges relative to centre. Restoring proper pressure and rotating tyres slows further edge wear.

Why Other Options Are Wrong:

• Near the centre: typical of over-inflation, not under-inflation.
• Lateral/cross-direction patterns: describe cupping or scalloping from imbalance/shock issues, not primarily pressure-related.
• Uniform wear: indicates correct inflation and alignment over time.

Common Pitfalls:
Confusing under-inflation edge wear with negative camber wear (usually one edge only); ignoring seasonal temperature changes that reduce cold inflation pressure.

Final Answer: