two surveys have been made of the conditions of tyres in use on cars and the following conclusions drawn. (1) about 9 per cent of cars have at least one tyre with a tread depth below the legal limit of 1 mm. (2) there are few cars with illegal combinations of radial and crossply tyres (certainly much less than 1 per cent).(3) there appear to be few cars with tyres exhibiting gross damage or structural failure. a full examination could not however be made during the surveys. (4) inflation pressure errors (i.e. the difference between that measured after correction and the recommended value) exceeding 8 p.s.i. in one or more tyres are to be found on about 13 per cent of cars and differential errors of the same amount (between two tyres on the same car) are to be found on about 17 per cent of cars. there is ample evidence that tread depths of less than 1 mm can lead to serious braking and steering difficulties under some wet road conditions. the effect on safety of inflation pressure errors of 8 p.s.i. or more are less well understood.

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