When to replace timing belt

every 60,000 miles or before.depends on driving conditions.if any of the below,before 60,000 Repeated short-distance driving Driving in dusty conditions Driving with extended use of brakes Driving in areas where salt or other corrosive materials are being used Driving on rough or muddy roads Extended periods of idling or low-speed operation Driving for long periods in cold temperatures or extremely humid climates