The tax does not apply to sales of tires of all-rubber construction (whether hollow center or solid) if they have no fabric or metal reinforcement and do not exceed either of these measurements: (a) 20 inches in diameter measured to the outside circumferences, and (b) 1 3/4 inches in cross-section. The exemption provided by section 4073(a) is to be determined solely on the measurements of the tire and not on the purpose for which it is designed or used.

(Secs. 4071(b), 4071(c), 4073(c), and 7805, Internal Revenue Code of 1954. (80 Stat. 331, 26 U.S.C. 4071(b); 68A Stat. 482, 26 U.S.C. 4071(c); 70 Stat. 389, 26 U.S.C. 4073(c); 68A Stat. 917, 26 U.S.C. 7805)) [T.D. 7809, 47 span 6007, Feb. 10, 1982]