An algebraic model has been developed that describes the decelerating forces that affect a pneumatic tyre in slip on a wet surface. The model is founded on an empirical extension to that for a tyre skidding on a wet surface.

The modelling of decelerating-force coefficient on a tyre in slip on a wet surface is dependent on twelve variables.

(i) Tyre dimensions

(ii) Tyre inflation pressure

(iii) Density of interface material

(iv) Rigidity modulus of interface material

(v) Rebound resilience of interface material

(vi) Vertical load

(vii) Ground speed

(viii) Slip ratio

(ix) Sharpness of surface micro-texture

(x) Surface temperature

(xi) Depth of surface macro-texture

(xii) Depth of water on surface

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. An adequate correlation is observed.