"Tread depth" shall mean the amount of tread design on the tire. Tread depth includes both original, retread and recap tread design; and, in respect to special mileage commercial tires, recut, re-grooved and siped tread design.
N.H. Rev. Stat. Ann. § 259:115
Tread Depth
Source
Official source: New Hampshire General Court. Reproduced from public-domain New Hampshire statutes; confirm against the official source for the current text. Not legal advice.