Abstract:

An algebraic model has been developed that describes the decelerating forces that affect a pneumatic tyre as it skids on a wet surface. The model is founded on an empirical extension to that for a dry surface.

For a specific design of tyre, it is supposed that the decelerating force in a full skid on a wet, paved surface depends on six variables

• Tyre inflation pressure
• Vertical load
• Ground speed
• Depth of surface macro-texture
• Sharpness of surface micro-texture and
• Water-depth

The pressure distribution in a wet footprint is assumed to consist of three zones, as described in ESDU TM 211, entitled "Pressures under wet footprint".

The adhesive decelerating force component is assumed to be negligible in the wet and the rigidity modulus for the interface layer is affected by the presence of water in the footprint.

Coefficient of decelerating-force values predicted by the model are compared with experimental measurements for a wide range of surfaces, tyre inflation pressures and operating speeds. A strong correlation is observed.