Patent ID: 7353150

Claim:
A method for designing a tire profile, comprising the steps of: inputting tire size data; determining a ratio (b/a) of a second axis radius “b” to a first axis radius “a” in an ellipse in which one of ends of a first axis is placed on a tire equator plane and a direction of the first axis is coincident with an axial direction of a tire; determining a constant of an involute function based on the tire size data in such a manner that an involute curve based on the ellipse having the ratio of (b/a) passes through a maximum width position of the tire and a central position in a lateral direction; and determining a profile curve reaching the maximum width position from the central position in the lateral direction based on the involute function having the constant; wherein the involute function is expressed in the following equations (I) and (II): x ⁡ ( θ ) = a ⁡ ( 1 + cos ⁢ ⁢ θ ) + b ⁢ ⁢ sin ⁢ ⁢ θ ⁢ 1 / ( a 2 ⁢ cos 2 ⁢ θ + b 2 ⁢ sin 2 ⁢ θ ) ⁡ [ S - ∫ π π - θ ⁢ ( a 2 ⁢ cos 2 ⁢ θ + b 2 ⁢ sin 2 ⁢ θ ) ⁢ ⅆ θ ] ( I ) and y ⁡ ( θ ) = b ⁢ ⁢ sin ⁢ ⁢ θ + a ⁢ ⁢ cos ⁢ ⁢ θ ⁢ 1 / ( a 2 ⁢ cos 2 ⁢ θ + b 2 ⁢ sin 2 ⁢ θ ) ⁡ [ S - ∫ π π - θ ⁢ ( a 2 ⁢ cos 2 ⁢ θ + b 2 ⁢ sin 2 ⁢ θ ) ⁢ ⅆ θ ] ( II ) (In the Equations (I) and (II), “a” represents the first axis radius of the ellipse, “b” represents the second axis radius of the ellipse and “S” represents a length of a thread wound upon the ellipse. θ is π/2 to π).