Wheels and Tyres

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Understanding which wheel you giving assistance to is important.

 

From an health and safety point of view a VRO / Agent will not always assist a vehicle, if the casualty has broken down on a motorway hard shoulder, where the operator is expected to work in the flow of traffic. Therefore you should always ask the Driver / Member who has broken down the following information. The information should be noted and passed to the VRO.

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• Near Side (N/S) is the wheel nearest the kerb or left hand side of the vehicle;

• Off Side (O/S) is the Driver side or side farthest from kerb.

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• Front axles (Steer Axle) always have a single wheel and tyre.

• Drive axles can have either a single or twin wheel combination. 

• Trailers can have Single, Twin or Super Single combination.

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When dealing with a breakdown relating to Wheels or Tyres, ask the following:-

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1. Which side of the vehicle is the wheel/tyre at fault?

2. On which axle?

3. Which part of the vehicle? I.E. Rigid, Tractor Unit or Trailer.

4. What is the tyre size?

5. If Twin wheel is it Inner or Out Tyre?
    

• 1st Axle  -  N/S – O/S* 

• 2nd Axle  - N/S – O/S* 

• 3rd Axle  -  N/S – O/S* 

• 4th Axle  -  N/S – O/S* 

 

When you have all the information you should have something as follows:-

 

• N/S Front (1st Axle) Tractor Unit – Size 295/80R 22.5
  or

• O/S Rear (2nd Axle) Inner, Trailer - Size 335/70R 22.5

 

The top tyre size would therefore be read as - 295  80R 22.5 when giving the information to a supplier.

 

• 295 - is the tyre width in mm.

• 80 - is the aspect ratio or tyre profile.

• R - means the tyre is of radial construction

• 22.5 - is the wheel rim diameter in inches