Spark plugs and wires should be replaced after 60,000 miles depending on the type of driving and the location where you live and drive.
50,000 miles.
How many miles should I have before I change my spark plugs
According to the owners manual, they have platinum plugs that should be changed at 100,000 miles.
Unless your ford focus is a diesel your car does not have glow plugs.
if the car is running rough or if plugs are in poor condition
Standard spark plugs, 50000 miles. Platinum tip spark plugs, 100000 miles.
120000 miles with original iridium plugs.
change the plugs at 60,000 miles.
Change the plugs at 100,000 miles or earlier if the engine is not performing as it should.
platinum plugs 75,000 miles. resistor plugs 30,000.
About every 50,000 miles.
Recommended change is 100,000 miles