Improper or inadequate vehicle maintenance can cause tires to wear abnormally. Here are some important maintenance points:
Tire Inflation Pressure
Inspect all tire pressure monthly (including the spare) when the tires are cold. Maintain recommended pressures for the best ride, top handling, and minimum tire wear. Use the pressures specified on the vehicle tire information placard or tire label for optimum service.
Tire Rotation
To equalize tread wear, rotate the tires every 12,000 km (7,500 miles) at the latest or sooner if irregular wear develops. Mazda recommends to rotate every 8,000 km (5,000 miles) to help increase tire life and distribute wear more evenly.

Do not include (TEMPORARY USE ONLY) spare tire in rotation.
Inspect the tires for uneven wear and damage. Abnormal wear is usually caused by one or a combination of the following:
After rotation, inflate all tire pressures to specification and inspect the lug nuts for tightness.
After adjusting the tire pressure, initialization of the tire pressure monitoring system is necessary to make the system operate normally.
CAUTION
Rotate unidirectional tires and radial tires that have an asymmetrical tread pattern or studs only from front to rear, not from side to side. Tire performance will be weakened if rotated from side to side.
Replacing a Tire
WARNING
Always use tires that are in good condition:
Driving with worn tires is dangerous. Reduced braking, steering, and traction could result in an accident.
If a tire wears evenly, a wear indicator will appear as a solid band across the tread. Replace the tire when this happens.

You should replace the tire before the band crosses the entire tread.
After adjusting the tire pressure, initialization of the tire pressure monitoring system is necessary to make the system operate normally.
NOTE
Tires degrade over time, even when they are not being used on the road. It is recommended that tires generally be replaced when they are 6 years or older. Heat caused by hot climates or frequent high loading conditions can accelerate the aging process. You should replace the spare tire when you replace the other road tires due to the aging of the spare tire. The period in which the tire was manufactured (both week and year) is indicated by a 4-digit number.
Safety Practices
The way you drive has a great deal to do with your tire mileage and safety. So cultivate good driving habits for your own benefit.
CAUTION
If you feel a sudden vibration or ride disturbance while driving or you suspect your tire or vehicle has been damaged, immediately reduce your speed. Drive with caution until you can safely pull off the road. Stop and inspect the tire for damage. If the tire is under-inflated or damaged, deflate it, remove the tire and rim and replace it with your spare tire. If you cannot detect a cause, have the vehicle towed to the nearest vehicle or tire dealer to have the vehicle inspected.
Glossary of Terms
Vehicle LoadingMazda 6 Owners Manual: Ignition switch inspection
1. Disconnect the negative battery cable.
2. Remove the column cover. (See COLUMN COVER REMOVAL/INSTALLATION)
3. Disconnect the ignition switch connectors.
4. Inspect for continuity between the ignition switch terminals using an
ohmmeter.
If not as specified, replace the ignition switch.
...
Mazda 6 Owners Manual: Drive belt auto tensioner inspection
1. Remove the drive belt. (See DRIVE BELT REPLACEMENT.)
2. Verify that the drive belt auto tensioner moves smoothly in the
operational direction.
Replace the drive belt auto tensioner if necessary.
3. Turn the drive belt auto tensioner pulley by hand and verify that it
rotates smoothly ...