tire wear bars are designed as visual indicators to tell you how much your tires' treads have worn down. New tires usually have 9/32nds to 11/32nds of an inch of tread depth, and as per tire ...

The low-resistance tread compound is molded into a symmetrical ... Engineers also specified the use of Stabilink connecting bars within the tires, which increase stability for enhanced performance ...

Manufacturers have made bald tires easier to spot by placing a series of molded horizontal bars at the base of the grooves. The bars become flush with surrounding tread when wear reduces a groove ...