The answer depends on the type of vehicle, driving conditions, and how well the tires have been maintained. Most tires are considered to have a life of between 25,000 and 50,000 miles before they need to be replaced. This is only an average, however. Tires should be inspected regularly for a proper evaluation.
If your tires have excessive or seriously uneven tread wear, cracked sidewalls, bulging spots, or discoloration, they probably should be replaced. Even if your tires look okay, if they are over 10 years old, they should probably be replaced, since tire rubber does degrade over time.
While it may seem cost-efficient to only replace the bad tire, it is actually better to replace all of the tires, especially if the tires have been in use for awhile. Today's suspension technology is designed to work best with a matching set of tires. When all tires are equal, your vehicle will handle more effectively and safely. At the very least, replace tires in pairs for best performance.
When replacing tires in pairs, the new tires should always be installed on the rear axle and the more worn tires moved to the front. New tires on the rear axle will allow the driver to more easily maintain control on wet roads because better treaded tires resist hydroplaning.
Tires lose about 1 psi of pressure per month and another 1 psi for every 10 degree drop in temperature.
In most cases it is recommended that tire air pressure be checked once a month for optimal tread wear, tire performance, and safety.
Tires do lose pressure - even when they are not in use. You should check your spare once a month, at the same time you are checking your other tires.
Every vehicle has a recommended tire pressure as set forth by the vehicle manufacturer. This information can be found in the vehicle owner's manual and on the inside driver side door jam.
It is not easy to tell if tire pressure is low simply by looking at your tires. The most reliable way to check them is by measuring the pressure with a gauge.
Premature tire wear can be caused by many factors including neglecting tire rotation, improper inflation, rough driving conditions, misalignment, worn vehicle parts and other issues. An experienced tire technician can usually tell what the problem is by looking at the tires.
Directional tires have a rotation arrow on the sidewall of the tire, indicating the direction in which the tire should turn. Directional tires should be used on one side of the vehicle and are supposed to be rotated from the front axle to the rear axle. In some cases, they can be dismounted and remounted on their wheels to accommodate use on the other side of the vehicle.
It is recommended that vehicles get an annual alignment checked annually. This is typically done at the same time as the recommended tire rotation. It is definitely a good idea to have an alignment done when you get new tires so they don't immediately start out wearing unevenly.