Section 7M. No person shall sell, offer or expose for sale, have in his possession with intent to sell, or give away, for use on any motor vehicle or trailer, on public highways any tire which: (a) has been retreaded or recapped unless such tire has been permanently marked on both sides thereof with the word ”retread”, ”retreaded”, ”recap” or ”recapped”; or (b) is of other than first quality unless such tire has been permanently marked on both sides thereof with a descriptive term indicating that the tire does not meet the manufacturer’s standard quality or appearance specifications for such brand of tire, such as: ”blem”, ”second”, ”imperfect” or similar appropriate descriptive term. The markings required hereunder shall be in letters at least three sixteenths of an inch in height and shall be so placed as to be plainly visible.