The Tread Wear Indicator Bar
Newer tires have a convenience that older tires lacked. They have tread wear indicator bars built into the tires themselves. These bars, invisible or barely visible when the tires are new, gradually begin to appear as the tread wears down. They appear as flat rubber bars running perpendicular to the direction of the tread itself. If more than one or two of these are visible on a tire, the tread is getting low. This should be particularly obvious in the wet tracks that your tires leave after you drive through a puddle. Use the penny test described on the previous page to double check the depth, but if the bars are starting to appear on any or all of your tires, it's once again time to check with your mechanic or local tire dealer to see about getting your current tires replaced.