31.—(1) For a Category B mobile crane, the maximum axle weight that may be specified on the plate fitted to it in accordance with paragraphs 15 to 18 is 12,500 kilograms.
(2) The maximum gross weight of a Category B mobile crane that may be specified on the plate fitted to it in accordance with paragraphs 15 to 18 is the number (expressed in kilograms) equal to the product of the following equation and then rounded up to the nearest 10 kilograms—
N × 12,500
(3) In sub-paragraph (2), N is the number of axles on the crane.