Tire
Tire means any agricultural, airplane, industrial, mobile home, light-duty truck and/or passenger vehicle tire that has a bead diameter less than or equal to 0.5 meter (19.7 inches) and a cross section dimension less than or equal to 0.325 m (12.8 in.), and that is mass produced in an assembly-line fashion.
Source
40 CFR § 60.541
Scoping language
All terms that are used in this subpart and are not defined below are given the same meaning as in the Act and in subpart A of this part.