On bus and lorry tyres, the sidewall code indicates what aspect of the tyre?

• A. Minimum Temperature
• B. Speed capability
• C. Tread Depth
• D. Running Pressure

Answer: (B)

The markings on a bus or lorry tyre’s sidewall tell you the tyre’s speed capability—the maximum safe speed the tyre is designed to run at while carrying its rated load. This speed rating is there because higher speeds generate more heat and stress, so tyres are rated to ensure safe performance under load. It’s not about running pressure (that comes from the vehicle’s placard or manual) or tread depth (which you check separately with wear indicators or measurements). So the sidewall code best indicates how fast the tyre can safely go.