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4.1 Tyres
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Information |
Method of Inspection |
Reason for rejection |
| This inspection applies toTyres fitted to the road wheels only. The vehicle presenter should be informed when it is noticed that there is a defective tyre on a spare wheel. | Type
of Structure On all the tyres fitted, check the 1. Nominal size and aspect ratio. Note: It cannot be assumed that there is a difference in the nominal sizes of tyres because either twin wheel is not in contact with the ground. Note: A Class III or IV vehicle tyre which appears to be of inadequate size, ply or speed rating for the vehicle or its use is not a reason for rejection. However, the vehicle presenter should be informed. |
1.
One tyre is of a different nominal size or aspect ratio to any
other on the same axle. Note: Special lightweight or space saving wheels and tyres fitted as a road wheel are reasons for rejection Note: Tyres with aspect ratios of 80% and 82% are almost indentical in size and can be safely mixed in any configuration on a vehicle. Where this is done, Reason for Rejection 1 does not apply. In all other cases of mixed aspect ratios on the same axle, rejection is justified. |
Identifying tyre size and type |
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| To
identify the size and type of tyres, it might be necessary to
rotate the wheels or move the vehicle. Only one sidewall of a tyre needs to be marked. |
2.
Type of structure, ie bias-belted, cross-ply or radial. Note: Steel and fabric radial-ply tyres are to be regarded as the same structure type. |
2.
a. one tyre is of a different type of structure from another tyre on the same axle b. a 3- or 4-wheeld vehicle fitted with single wheels, and i. a cross-ply tyre or bias-belted tyre fitted on rear axle and radial-ply tyre is fitted on front axle, or ii. a cross-ply tyre fitted on rear axle and a bias-belted tyre fitted on front axle. Note: Any tyre ‘type’ mix between different axles is acceptable for vehicles that have . 2 axle and ‘twin’ wheels on the rear axle . 3 axles, one steering and one driving Note: This does not apply to vehicles with an axle fitted with “super single” tyres having a road contact area at least 300 mm wide. |
Section height:section width ratio (aspect ratio) |
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| Unless marked otherwise, “standard” car tyres have a nominal aspect ratio of 82%. Some tyres have an aspect ratio of 80%. These have “/80” included in their size marking eg 165/80 R13. | ||
Dual size marking of tyres |
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| Some
tyre manufacturers are now dual marking certain sizes of tyres. For example, a 185/75R14 tyre may be dual marked 185R14. Where a tyre is found to be dual marked by the manufacturer on the side-wall, either markings can be accepted. |
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B. Load Index and Speed Rating (Applicable to Class VII only) |
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| Permitted
laden weight of an axle This is the relevant axle weight in the column headed ‘WEIGHTS NOT TO BE EXCEEDED IN GT BRITAIN’ (GB WEIGHTS) shown on the Department of Transport plate (Ministry plate) fitted to the vehicle. |
B. Load Index and Speed Rating (Applicable to Class VII only) | |
| a.
check for a load index (or ply rating and tyre size) marked
on at least one sidewall of each tyre. (See pages 9 &
10 for the indentification of tyre load index, ply rating and
tyre size) Note: A tyre not marked with a load index or ply rating is assumed to have the lowest ‘load capacity’ of its size. |
1. a. a tyre not marked with its size on at least one sidewall. (See pages 9 & 10) |
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| b. check the load index is adequate for the maximum laden weight of the axle. | b. a tyre that has a load index (or ply rating and tyre size) that is inadequate for the permitted maximum laden weight of the axle to which it is fitted. (See pages 9 & 10 for the determination of tyre load capacity) | |
Vehicles not fitted with Ministry plate |
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| f a Ministry
plate is not fitted to the vehicle, the relevant axle GB WEIGHT
is that shown on the manufacturer’s plate (See section 3, page
27). Some vehicles first used before 1968 might not be fitted with a Ministry plate or a manufacturer’s plate displaying axle weights. The load capacity of tyres on such vehicles must be assumed suitable, unless there is indisputable evidence to the contrary. |
2. Check for a speed rating letter marked on the sidewall of each tyre | 2. A tyre marked with one of the following speed rating letters: A, B, C, D, E, F, G, J or K. |
| Note: Some tyres are not marked with a ‘speed rating’ and the absence of such a mark is not a reason for rejection. | ||
C. Condition of Tyres |
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| Inspecting
the tyres It is not possible to see every part of a tyre, in particular the tread contact area, when twin wheels are fitted or when the body shrouds the tyres. If necessary, the vehicle must be moved to expose the hidden parts and the examination completed from under the vehicle. |
C. Condition of Tyres | |
| 1. Examine each tyre for | a. a tyre has a cut the length of which is at least 25 mm or 10% of section width, whichever is greater, deep enough to reach the ply or cords | |
| a. cuts | ||
| b.
lumps, bulges, tears, exposure of the ply or cord, or tread
separation Note: On radial ply tyres, care should be taken to distinguish between normal undulations in the carcass, resulting from manufacturing, and lumps or bulges caused by structural deterioration |
b.
a tyre hasa lump, bulge or tear caused by separation or partial failure of
its structure. This includes any lifting of the tread
rubber any of its ply or cord exposed |
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| c. a recut tread | a re-cut tyre fitted to a vehicle not permitted to be so equipped | |
| d. incorrect seating in the wheel rim | d. a tyre incorrectly seated on the wheel rim | |
| e. valve condition and alignment | e. a seriously damaged or misaligned valve stem which could cause sudden deflation of the tyre | |
| f. correct fitting | f. a tyre not fitted in compliance with the manufacturers sidewall instruction, eg an asymmetric tyre with a sidewall marked ‘outer’ fitted with the marking to the inner side of the wheel | |
| g. under-inflationNote: Under-inflation of a tyre is not in itself a reason for rejection. However,a brake test might be inadvisable, because of possible damage, ora headlight test might be affected, if the under-inflation is affecting alignment | ||
Recut tyres |
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| Recut
tyres are permitted on a goods vehicle at least 2540 kg unladen weight having at least 405 mm (16 inch) diameter wheels a vehicle with at least 8 passenger seats, excluding the driver’s seat, and over 2540 kg unladen weight a vehicle over 3050 kg unladen weight |
2. Check tyres for fouling a part of the vehicle. | 2.
A tyre fouling a part of the vehicle. Note: This does not apply to vehicles designed to permit tyre contact with the chassis or frame eg. Steering lock stop function. |
| 3. Check tyres on twin wheels for wall contact. | 3.
Tyres on twin wheels making wall contact due to under-inflation
or incorrect fitment. Note: Some tyres, eg radial ply tyres, with flexible side walls may touch under load. Wall contact in these circumstances is not a reason for rejection. |
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D. Breadth and depth of tread |
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| Tread A tread pattern is the combination of plain surfaces and grooves extending across the breadth of the tread and round the entire circumference. 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. |
D.
Breadth and depth of tread1.6 mm tread depth 1. Check the tread pattern over the complete circumference of the tyre. Check also that the tread depth meets the requirements using, as necessary, a depth gauge accepted for MOT testing. |
1.
The grooves of the tread pattern are not at least 1.6mm throughout
a continuous band comprising . the central three-quarters of the breadth of tread, and . round the entire outer circumference of the tyre Note: Each side of the central band of the tyre can be devoid of tread (ie. ‘bald’) and still meet the pass standard although in practice such tyre wear is unlikely to occur. See diagram below |
Breadth of tread |
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| 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. | ||
A 1.6 mm minimum tread depth applies to |
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| A
vehicle first used after 2 January 1933 that is either a. a passenger carrying vehicle (car, motor caravan etc) with not more than 8 passenger seats, excluding the driver’s, or b. a goods vehicle or dual purpose vehicle not exceeding 3500 kg maximum gross weight |
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A 1.0mm minimum tread depth applies to |
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A passenger-carrying vehicle with more than 8 passenger seats
excluding the driver's seat. - A vehicle first used before 3 January 1933. |
2. Check the tread pattern over the complete circumference of the tyre. Check also that the tread depth meets the requirements using, as necessary, a depth gauge accepted for MOT testing. | 2.
A tyre with a tread pattern a. not visible over the whole tread area, and b. the depth of which is not at least 1 mm throughout a single band . round the entire outer circumference of the tyre . of at least three-quarters of the breadth of tread Note: The 1.0 mm tread depth requirement applies to the whole tread width if the original tread pattern did not extend beyond three-quarters of the tyre tread width when new |
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Reproduced from the MOT Inspection Manual by kind permission of THE VEHICLE INSPECTORATE.
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