Hennie Botha, Director Fleet, at Key Hire takes a special interest in road safety and steering tyres. Says Botha – “Loss of directional control due to steering tyre failure is a significant contributor to road crashes. On trucks and buses, steering tyres are subject to different pressure ratings when compared to drive axle tyres. In addition, steering tyres never achieve the same distance as drive axle tyres. And never ever fit a recap tyre to a steering axle.”

Botha adds – “Because the steer axle is used to steer a bus or truck, it is essential for tyres to have good steering properties. Steering must take place smoothly. Steering axle tyres are directional to keep a vehicle in the right direction – this requires a different tread pattern to a drive axle traction tyre.”

Here are a few guidelines that Botha recommends:

  • Develop an in-house steering axle tyre policy and SOP (standard operating procedure)
  • Steering axle tyres must displace water – tread depth must not be less than 4mm across the entire tread pattern. 3mm is the absolute minimum pull point (extract from steering service).
  • Steering tyre pressures must be measured on cold tyres – bleeding a hot tyre is forbidden – a loaded hot tyre will gain as much as 20% kPa on a hot day.
  • Tyre pressure reading and pressure adjustment must not be left at sole discretion in the hands of a pump jockey (Petrol pump attendant) – the driver is responsible/accountable for accurate pressures and the driver must be aware (Educated / Trained on this issue) of significant tyre pressure differentials and possible reasons for a pressure differential, especially when tyres are being checked and inflated.
  • Valve caps must always be fitted – steel caps preferred. The valve stalk must not be under stress such as bent sideways or damaged. All valves, especially dual tyres, must be accessible.
  • At every long-distance stop the driver must conduct a quick walk-around inspection of all tyres with a focus on the steering axle for the following:
  • - Valve caps are present
    - Touch test – tyres warm-up in service but a tyre that is seriously under-pressured develops excess heat and will be very hot in relation to other tyres on the vehicle
    - No stones or objects jammed into the tread pattern
    - No visible sidewall cuts, bulges, or unusual deformation of the tread belt

These guidelines comply with and are in addition to Regulation 212 of the National Road Traffic Act.

If you wish to discuss this or for a copy of a steering tyre SOP, please contact Hennie Botha at 031 713 3146 or at 074 331 1354.