When it's worn out!
100,000 miles
The Gates website ( they make timing belts etc. ) shows : Inspect at 120,000 miles , replace as necessary for the 2.5 liter four cylinder in a 2000 Ford Ranger ( But in general , for all vehicles they show to replace every ( 6 years or manufacturers recommended mileage which ever comes first )
I believe the 2.3 L - DOHC engine in the 2004 Ford Ranger has a timing CHAIN instead of a timing belt , the 3.0 L and 4.0 L use timing chains
You cannot tell that is why you just replace them at a set mileage as recommended by the manufacture of the vehicle.
It is recommended that you replace the timing Chang, on your Chevrolet Silverado pickup truck, at 60,000 miles. Many times the warranty is voided if the timing chain is not changed.
The current factory recommended replacement mileage is 105,000 miles.
On the Peugeot 207 1.6 HDi, the timing belt is recommended to be replaced after 10 years or 100,000 miles.
RECOMMENDED BETWEEN 60, 000 kms and 80, 000kms * Replace engine timing belt (Except vehicles with timing chain)
every 90,000 miles average to replace timing belt
Belt. Recommended replacement mileage: 90,000 miles. Do yorself a favor and replace the water pump at the same time.
60000 miles
check recommended mileage, DO NOT EXCEED