HC Deb 26 October 1979 vol 972 c323W
Mr. Critchley

asked the Minister of Transport if he is satisfied that the legal requirement of at least 1mm. of rubber on the tread of a tyre is enough to encourage safety.

Mr. Kenneth Clarke

I am satisfied that this is a reasonable standard. Research by the transport and road research laboratory suggests that there would be no significant safety advantage in increasing the minimum tread depth.