As a general rule, above what width must a lorry be fitted with end-outline marker lights?

Correct answer

When its width exceeds 2.10 metres.

On a lorry, end-outline marker lights are compulsory when width exceeds 2.10 metres; fitting is optional between 1.80 and 2.10 metres. They are white at the front and red at the rear. Fitting requirements are separate from use: switch them on at night, in substantially reduced visibility and in tunnels or underpasses.