The tires are one of the most important parts of the vehicle chassis, as they significantly influence aspects such as vehicle's directional stability, braking performance, ride comfort, NVH, and fuel consumption. The tires are also a part whose size affects the vehicle's essential specifications such as wheelbase and track width. The size of the tires should therefore be determined in the initial stage of vehicle development, taking into account whether the size allows the vehicle to achieve the targeted overall performance.In estimations of vehicle performance, computer simulation plays more of an important role, and simulated tire models are designed to reproduce the measured tire characteristics of existing tires. But to estimate the chassis performance with various tire sizes or with tires of uncommon sizes, the prevailing modeling approach, “individual models for individual tires,” would not function well because of limited ability to expand tire models to unfamiliar sizes.To solve the above problem, we propose a new tire modeling method that enables estimation of a tire's average characteristics by simply specifying tire size and conditions such as inflation pressure and load. This tire model, called a “statistical tire model”, is derived from a large number of measurement data for a variety of tire sizes, and can make rough estimation of major tire characteristics such as cornering stiffness, vertical stiffness, and dynamic loaded radius. By utilizing this tire model, appropriate tire size can be determined in the initial stage of vehicle development.