18.—(1) Except as stated in paragraph 19, an AILV that falls within paragraph 3(c) or (d) may be used on roads only for, or in connection with, the towing of another AILV which is a trailer.
(2) Where the overall width of such a towing vehicle exceeds 3 metres, it must not be used unless—
(a)the trailer it is towing has an overall width exceeding 3 metres; and
(b)the load can only safely be carried on such a trailer.