Abstract: A method and apparatus for determining the conicity of a tire wherein, while the tire is being corrected for radial force variation by grinding as it revolves in a first direction, the lateral thrust force of the lateral force variation is determined and stored. The tire is revolved in a second direction and the lateral thrust force is determined. The conicity of the tire is calculated by use of the post grinding lateral thrust force values and then is compared to a predetermined maximum allowable conicity. The tire is graded accordingly. Associated circuity and apparatus are disclosed.