Styrene–butadiene rubber (SBR): identify the application from the list below for which SBR is never used in standard practice.

Introduction / Context:
SBR is a general-purpose synthetic rubber valued for abrasion resistance and cost effectiveness. It is ubiquitous in passenger car tyres, footwear, mats, and coated fabrics. However, the extreme demands of aircraft tyres—very high load, speed, temperature rise, and cyclic stress—necessitate specialized rubber formulations dominated by natural rubber (NR) or advanced blends, not conventional SBR as the primary elastomer.

Given Data / Assumptions:

• Aircraft tyres experience severe heat build-up and require exceptional fatigue/crack growth resistance.
• NR has superior strain-induced crystallisation and tear resistance vs. SBR.
• SBR is common in many general-duty applications but not in heavy-duty aircraft tyre treads.

Concept / Approach:
NR’s unique strain-crystallisation provides outstanding cut/tear resistance and resilience, making it the material of choice for aircraft tyre carcasses and treads. SBR lacks comparable fatigue performance under aircraft duty cycles. Hence, “front-wheel tyres of aeroplanes” (representing heavy-duty aircraft tyres) is outside SBR’s typical use envelope. In contrast, SBR latexes and solids are widely used in coated fabrics, shoe soles, gaskets, and vibration-damping parts where performance demands are compatible.

Step-by-Step Solution:

Verification / Alternative check:
Tire engineering references specify NR-rich compounds for aircraft tyre treads and carcasses due to heat build-up, load, and safety margins.

Why Other Options Are Wrong:

• Coated fabrics/gaskets/soles/damping pads: all established SBR applications.

Common Pitfalls:
Assuming automotive tyre practice (SBR blends) directly transfers to the extreme aircraft service environment.

Final Answer:
Front-wheel tyres of aeroplanes (heavy-duty aircraft tyres)