Tyres and road wheels:

Spare wheels and tyres are not testable. Space saver type spare wheels fitted to the vehicle at the time of test will fail.

Tyres must be free from cuts over 25mm long that penetrate to the cords. Exposed cord, lumps and bulges caused by tread separation are also causes of failure.

They must also be fitted properly to the rim and in accordance with the manufacturers markings i.e a tyre marked inner with that side fitted to the outer.

Tyre pressure is not testable but a partially deflated tyre may cause failure because brake testing and headlamp aim couldn't be carried out.

The tread pattern excludes any tie-bars, tread wear indicators or other features designed to wear out substantially before the remainder of the pattern and other minor features.

The breadth of the tread is the part of the tyre which can contact the road under normal conditions of use measured at 90 degrees to the peripheral line of the tread (the tyres footprint).

There are two tread depths applicable:

Vehicles with up to eight seats excluding the driver first used after 2nd January 1933 must have 1.6mm of tread, 3/4 of breadth centred on the middle of the tyre in a continous band for the full circumference.

Cars first used before 3rd January 1933 and vehicles with more than eight seats excluding the driver only require 1.0mm of tread, in a continous band throughout the full circumference on any 3/4's of the breadth. However, the remaining 1/4 must still have the base of the original tread pattern clearly visible throughout the full circumference of the tyre.

Tyre capacity, load index and ply rating are testable items on Class VII goods vehicles over 3000kg and up to 3500kg design gross weight but not on cars.