What is the minimum tread depth across the central three-quarters of the width of a lorry tyre?

What is the minimum tread depth across the central three-quarters of the width of a lorry tyre?

• A. 1.5mm
• B. 2.5mm
• C. 1mm
• D. 5mm

Answer: (C)

Tread depth is what gives the tyre grip and helps push water away from the contact patch. The central three-quarters of the width matter most because that is the part of the tyre that bears most of the load and maintains contact with the road during braking and cornering. The minimum depth allowed there is one millimetre. This depth still provides some ability to channel water and maintain grip, but once you wear below it, the risk of slipping and aquaplaning increases rapidly, especially in wet conditions. The other options would mean more tread than the required minimum. Since the question asks for the minimum allowable depth, those deeper values aren’t correct for this context. Note that in many jurisdictions the commonly cited legal minimum is higher (often 1.6 mm across the central three-quarters), so always check local regulations.

Tread depth is what gives the tyre grip and helps push water away from the contact patch. The central three-quarters of the width matter most because that is the part of the tyre that bears most of the load and maintains contact with the road during braking and cornering. The minimum depth allowed there is one millimetre. This depth still provides some ability to channel water and maintain grip, but once you wear below it, the risk of slipping and aquaplaning increases rapidly, especially in wet conditions.

The other options would mean more tread than the required minimum. Since the question asks for the minimum allowable depth, those deeper values aren’t correct for this context. Note that in many jurisdictions the commonly cited legal minimum is higher (often 1.6 mm across the central three-quarters), so always check local regulations.