4.1 Tyres

Information Method of Inspection Reason for rejection
Spare tyres are not included in the inspection. However, if a defect is seen, the vehicle presenter should be notified.

The owner should be advised of loose or missing security bolts.

Serious under-inflation of tyres is not a reason for failure. However, the tester may decide not to conduct a brake test if tyre damage is likely, or a headlamp test if alignment could be affected. Advise the owner.

A tyre repair may be drawn to the attention of the vehicle presenter.

Examples of unsuitable tyres:
a. side car tyres or car tyres on a solo machine (note side car outfits may be fitted with 'solo' type tyres on any wheel);

b. Motocross or similar tyres, i.e. tyres where the space between tread blocks is substantially greater than the size of the blocks themselves; which do not have MST (multi service tyre) with an 'E' in a circle or an 'e' in a rectangle moulded into or on to the tyre wall

c. tyres designated by their manufacture as unsuitable for road use e.g. racing tyres or those marked 'NHS' or 'NOT FOR HIGHWAY USE' on the sidewall.

d. a tyre specifically designed for front wheel use fitted to the rear wheel;

e. a bias belted tyre fitted to the front with a cross-ply tyre fitted to the rearwheel

f. a radial tyre fitted to the front and a cross ply or bias belted tyre fitted to the rear wheel

On radial tyres
care should be taken to distinguish between normal manufacturing undulations in the carcass and lumps or bulges caused by structural deterioration.

Where the engine capacity is not greater than 50cc, tread depth may be less than 1mm, if the tread pattern is clearly visible around the entire circumference and across the whole breadth of the tread.

Directional tyres
these tyres must be fitted in accordance with the instructions on the sidewall. The direction of forward rotation is indicated by an arrow, words or both.

Tyres which do not meet the three-quarters width rule when new must have a minimum of 1mm tread over the whole of the original tread pattern.

'Breadth of tread' means that part of the tread which can contact the road in normal use, including cornering.

'Tread pattern' excludes tie-bars, tread wear indicators, features designed to wear out substantially before the rest of the pattern and other minor features. Original tread pattern must be takeninto account when assessing tread wear.

The position of tread wear indicators are normally marked 'TWI' on the sidewall of the tyre in line with the tread wear indicator.
1. Examine the tyres for type and suitability. (see information column)

2. With the wheels raised clear of the ground, rotate each slowly and examine each tyre for:

a. cuts, lumps, bulges, tears or exposure of the ply or cord, separation of the tread

b. incorrect seating in the wheel rim

c. valve condition and alignment

d. recutting of the tread

e. fitment in the correct direction of rotation

3. Check that there is a visible tread pattern around the complete circumference of the tyre. Ensure that the tread depth meets the requirements using a depth gauge.

4. Check for signs of fouling of tyres on other components.
1. An unsuitable tyre. (see information column )

(i) A tyre has a cut longer than 25mm or 10% of the section width of the tyre, whichever is the greatest, and deep enough to reach the ply or cord.
(ii) A tyre with a lump, bulge or tear caused by separation or partial failure of its structure, including lifting of the tread. (see information column).
(iii) Any ply or cord exposed b. a tyre not correctly seated in the wheel rim

c. a seriously damaged or misaligned valve stem which could cause sudden deflation of the tyre

d. a tyre with a recut tread

e. A tyre not fitted in accordance with the direction of rotation marked on the sidewall (see information column).

(i) the tread pattern is not clearly visible over the whole tread area. (see information column)
(ii) The depth of face="Arial, 1 mm throughout a continuous circumferential band measuring at least three quarters of the breadth of the tread. (see information column).

4. A tyre fouling another component.
A Metzeler 100/80 - 17 52s ME22 tyre is suitable for fitment to the rear wheel of an Aprilia AF 50 motorcycle provided it is fitted in the reverse to the direction of rotation indicated on the tyre wall.  

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