Tyres, wheels and hubs
10-1 Tyres and wheels
Reasons for rejection
Mandatory and permitted equipment
1. Refer to general vehicle pages.
2. On a groundspreader or dedicated groundsprayer fitted with multiple tyre sets that are made up of tyres of different size or construction:
a) the tyre sets are not fitted so that those fitted at one end of the axle mirror those fitted at the other end of the axle.
3. The tyres on an axle do not meet at least one of the following:
a) the tyre ply ratings:
i. are the same on a class MD3 vehicle
ii. differ by no more than two on a vehicle of other than class MD3
b) the tyre load indices:
i. differ by no more than two on a class MD3 vehicle
ii. differ by no more than six on a vehicle of other than class MD3
c) where no load index is indicated, the tyre load ratings (kg) on an axle differ by no more than 21% of the lowest rating.
Condition
4. Refer to general vehicle pages.
5. A tyre shows damage that is likely to compromise its ability to operate in a safe manner or lead to premature tyre failure, such as:
a) a lump or bulge that is likely to be caused by separation of the tyre structure, or
b) a cut or crack in a side wall or tread more than 25mm long that reaches the cords (see (Note 2) for visible cords in the tread area of heavy vehicle radial-ply tyres), or
c) exposed or cut cords (see (Note 2) for visible cords in the tread area of heavy vehicle radial-ply tyres), or
d) the tread of a retreaded tyre shows signs of separation, or
e) nails or other sharp objects embedded in the tyre, or
f) significant perishing, eg due to age, moisture or exposure.
Modification and repair
6. A modification or repair affects the tyres and wheels and:
a) is not excluded from the requirements for HVS certification (Table 10-1-4), or
b) the modification is not for the purpose of law enforcement or the provision of emergency services, or
c) is missing proof of HVS certification, ie the vehicle has been modified or repaired, and:
i. no LANDATA record has been entered, or
ii. no valid LT400 form from an HVS certifier of category HVEC or HMCD has been presented.
Note 1 Definitions
Central tyre inflation system means a type of tyre pressure control system that adjusts tyre pressure for the purpose of inflating and deflating tyres to improve tyre adhesion and reduce road surface damage and is under the central control of the driver or an automated system, or a combination of both the driver and an automated system (commonly known as ‘CTI’).
Dedicated groundsprayer means a self-propelled or trailing machine whose sole function is the application of chemicals or liquid fertiliser to crops or to the ground.
Groundspreader means a vehicle designed specifically for the carriage of powder or particulate artificial fertilisers on the road, and for the distribution of those fertilisers directly from the vehicle onto the land by means of a mechanical or pneumatic distributor that forms part of the vehicle.
Protective belt, sometimes called a protective ply or breaker, means an optional layer of ply material (cords) located immediately under the tread to minimise damage to the structural belts beneath.
Note 2
Where a heavy vehicle radial-ply tyre has visible cords in the tread area, the vehicle inspector may pass such a tyre for CoF provided the tyre is in a safe condition, eg only the protective cord layer (protective belt, see Figure 10-1-5) is visible. When determining whether such a tyre is in a safe condition, the vehicle inspector may take into account written evidence from a person who has current specialist tyre knowledge and experience, particularly in heavy vehicle tyre inspection.
Table 10-1-4. Requirements for HVS certification
HVS certification is required | HVS certification is not required |
|---|---|
1. Increase of track width beyond vehicle manufacturer’s specified limits. 2. Fitting of tyres additional to the limit specified by the vehicle manufacturer. 3. Modified wheels (including fitting of different rims). | 1. Modified wheels with written evidence from the vehicle manufacturer that the complete assembly of tyre, hub and axle is within the vehicle manufacturer’s operating limits. Such approval is likely to contain the approved tyre and wheel sizes and the maximum track, separately for all axles, together with the maximum number of wheels fitted to one axle, and may also include a few restrictions such as reduced axle load and so on (see Technical bulletin (CoF) 2). 2. Retrofitting a tyre pressure control system in accordance with the equipment manufacturer’s instructions. 3. Fitting a regrooved tyre identified as specifically designed and constructed for the process of regrooving after manufacture. |
4. Any modification or repair likely to have been carried out before 1 January 1997 (modifications and repairs before this date generally required certification but for inspection purposes no evidence of this is required). 5. Any repair or modification not listed in the left-hand column unless the vehicle inspector considers that certification is required because the modification or repair has affected the vehicle’s safety performance (a second opinion from an expert may be needed, eg the manufacturer’s representative, or a reputable workshop). |
Figure 10-1-5. Cross-sectional representation of a heavy vehicle radial-ply tyre
Summary of legislation
Applicable legislation
Mandatory and permitted equipment
1. Refer to general vehicle pages.
2. Individual tyres of multiple tyre sets on groundspreaders or dedicated groundsprayers may be of different sizes or construction in the same set, but each multiple tyre set must be the same as the other multiple tyre set on the same axle.
Condition
3. Refer to general vehicle pages.
4. A heavy vehicle radial-ply tyre may have visible cords in the tyre tread area provided the tyre is in a safe condition. To assess whether such a tyre is in a safe condition, the vehicle inspector may take into account written evidence from a person who has current specialist tyre knowledge and experience, particularly in heavy vehicle tyre inspection.
Modification and repair
5. A modification or repair that affects the tyres or wheels must be inspected and certified by an HVS certifier of category HVEC, HVMC or HVIC, unless the vehicle:
a) is excluded from the requirement for HVS certification (Table 10-1-4), and
b) has been inspected in accordance with the requirements in this manual, including those for equipment, condition and performance.
Page amended 1 April 2023 (see amendment details)