16 CFR 1512.11: Requirements for wheels.

(a) Spokes. There shall be no missing spokes.

(b) Alignment. The wheel assembly shall be aligned such that no less than 1.6 mm ( 1/16 in.) clearance exists between the tire and fork or any frame member when the wheel is rotated to any position.

(c) Rims. Rims shall retain the spokes and tire when side-loaded with 2000 N (450 lbf) and tested in accordance with the rim test, § 1512.18(j). Sidewalk bicycles need not meet this requirement.