You can rely on the wear indicators across the tread if the tires are otherwise in good condition. Good condition being: even, correct wear on the tread. sidewalls in good condition: no cuts, cracks or bulges. even if the tires look to be in good contition they can still be to old to be safe (the manufacture date is coded in the last four digits of the tires ID number, first two- week of the year, last two- year)