Maryland Code, Transportation § 22-405

(a) A person may not drive a motor vehicle on any highway unless the motor vehicle is equipped with tires in safe operating condition, in accordance with requirements approved by the Administrator.

(b) A person may not drive a trailer on any highway unless the trailer is equipped with tires in safe operating condition, in accordance with requirements approved by the Administrator.

(c) The Administrator shall adopt rules of safe operating conditions capable of being employed by a police officer for visual inspection of tires maintained on vehicles, including visual comparisons with simple measuring devices. The requirements shall encompass effects on tread wear and depth of tread.

(d) If a police officer, at any time, has reasonable cause to believe that a vehicle is unsafe or equipped with tires in violation of the provisions of this section, the police officer may require the driver of the vehicle to stop and submit the vehicle tire to an inspection. If the inspection discloses the vehicle to be in violation, the officer may issue a summons for the violation.