US Patent 7557694 Vehicle tire tread depth determining system

A vehicle tire tread depth determining system includes an annular member embedded beneath an outer surface, and disposed beneath a tread layer, of a vehicle tire. The member has photo-chromatic properties that change color when exposed to ultraviolet light. The member also has a body extending inside an outer perimeter of a tire, and is spaced from the tread layer and formed therewith. A color determining mechanism is in visual communication with the member. A time period mechanism determines when the member has transgressed from a first color to a second color. A display screen is mounted on the dashboard, and includes a graphical user interface and a pictorial illustration of the member color. A controller is housed within a compartment of the vehicle and positioned on a dashboard. A tread depth determining mechanism is spaced from the tire and electrically coupled to a battery and an ignition controller.