ESDU 15003 comprises methods for predicting the speed at which an aircraft-type tyre experiences planing when travelling on a water-covered runway surface. The methods were developed after it became apparent that the frequently-used VP = 9 p relationship for planing was inappropriate in numerous investigations. Two types of planing are defined: partial planing@ which is manifested by a reduction in the water spray ejected by a tyre@ tyre spin-down and the fluid drag force reaching its peak value@ and complete planing@ which results in a loss of contact between the tyre footprint and ground surface@ a loss of directional stability and a loss of braking action. Mathematical relationships for determining the speed at which each type of planing occurs are provided. The methods are empirical in nature and are the results of a comprehensive analysis of the planing of rib-tread aircraft tyres on water-covered runway surfaces. Their development is outlined in detail.