Custom road surface files are often required to simulate discrete or continuous ride and durability events. 2D road surfaces are the simplest means of simulating discrete, and some types of continuous events. Types of 2D surfaces are Flat, Plank (Cleat), Drum, Polyline & Sine. Polyline road surfaces are versatile due to user-definable profile. Typical format of polyline 2D road surface files for both point & line contact tire models involves an array of longitudinal vs vertical co-ordinates.