The Motor Vehicles (Tests) Regulations 1981

9.  The vehicle shall be examined to ascertain whether its tyres comply with the tyre requirements and in particular to ascertain whether—

(a) except in the case of a heavy motor car, any tyre is a recut pneumatic tyre;

(b) any tyre is unsuitable having regard to the types of tyres fitted to its other wheels;

(c) any tyre has a break in its fabric, or has a cut in excess of 25 millimetres or 10 per cent of the section width of the tyre, whichever is the greater, measured in any direction on the outside of the tyre and deep enough to reach the body cords;

(d) any tyre has any lump or bulge (caused by separation or partial failure of its structure) or any exposure of the ply or cord structure;

(e) in the case of a motor cycle whereof the cylinder capacity of the engine does not exceed 50 cubic centimetres, the tread of each tyre shows throughout at least three quarters of the breadth of the tread and round the entire outer circumstances of the tyre a pattern the relief of which is clearly visible, and in the case of any other vehicle the tread pattern (excluding any tie bar) of each tyre has a depth of at least 1 millimetre throughout at least three quarters of the breadth of the tread and round the entire outer circumference of the tyre;

(f) there is any other defect in any tyre or any defect in any roadwheel by reason of which the tyre requirements are not complied with.