^49 CFR 523.2 - Definitions., U.S. Code of Federal Regulations, Cornell University Law School, [2014-12-04], (原始内容存档于2023-05-31), Approach angle means the smallest angle, in a plane side view of an automobile, formed by the level surface on which the automobile is standing and a line tangent to the front tire static loaded radius arc and touching the underside of the automobile forward of the front tire.