Abstract
Automobile hydroplaning speed is affected by both the vehicle load on the tyre and its inflation pressure, yet only inflation pressure is valued in Horne's (1968) equation. In 1984 modifications were made to include a vehicle's tyre footprint characteristics. Dunlop and others (1974) studied the influence of water depth and tread depth on an automobile's hydroplaning speed. Empirical studies by Gallaway and others (1979) produced more conclusive hydroplaning speeds for both automobiles and Ivey and others (1984) for trucks. This paper uses an influence diagram to show how all the models are related. Using the model a few vehicle design parameters are pursued that may be combined to make vehicles more prone to hydroplaning.